What Causes Deformed Chicken Eggs and Other Egg Abnormalities?

When You're Raising Laying Hens, You May See Some Strange Eggs Like These

Egg abnormalities and deformed chicken eggs occur with almost every breed of hen at some point in her egg laying career. Eggs laid by non-commercially bred hens vary considerably in size, shape, and color. People who have a small flock of backyard chickens with several different chicken breeds can learn to recognize eggs from each hen. It’s easier for them to know who’s laying and who isn’t, how often and when, and which hen may be having health issues because of consistent abnormalities. For people like me who have a larger flock,  it’s harder to tell and requires us to separate a suspected hen to determine her laying quality and quantity.

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The Anatomy Of Egg Laying

If you butcher your own birds and any of them are of egg laying age (5 to 7 months for most all breeds), you’ll see the eggs waiting inside her. There’ll be a cluster of little tiny yellow specks that look like grains of sand with small pebble like ones around them, graduating in size, larger and larger. These are the yolks. Have you ever wondered how do chickens lay eggs? When the yolk for the day is ready, it enters the oviduct where it can be fertilized.

Next, the egg white is added, then it receives two membranes that help to keep the nutrients in and to keep its shape. Finally, the shell is put on and the egg moves to just inside her vent. The whole process takes about 24 hours. Now, she’s ready to lay! Boy will she let you know when she’s done it. My whole flock gets excited and cackles for each and every egg, every day. You would think they would be used to doing it and not put on such a show, but it’s a production of cackles and crows for every egg! This is a very basic and simple explanation of the egg production process and somewhere in this straightforward, yet complex process, things happen that cause deformed chicken eggs and egg abnormalities.

Just in way of a reminder, a pullet (a hen under a year old) will lay smaller eggs than she will as she grows and matures into a hen. Of course, age is the first thing that comes to mind since most chicken breeds begin laying between 5 to 6 months of age. As a hen matures, the size of her eggs and the frequency of her laying will increase. Once she begins laying, it usually takes her 7 to 10 weeks to work up to full production. Depending on the breed and the lifestyle of your hen, you can expect her to lay for up to 10 years. The average lifespan of a hen is 14 years. If your main goal is egg production, then you probably wouldn’t want to keep your hen past 3 to 4 years of age as this is the age range she will be most productive. When I have a hen who is unproductive for more than four months out of the year, I cull her. That is of course unless she is special.  

Deformed Eggs

Who’s Laying And Who’s Not

Judging which hen is laying and which isn’t is not an exact science, but there are some signs. Before a hen begins to lay, you will see a yellow color around her vent, eyes and earlobes. After she has been laying for a few months, the yellow in these and her beak will fade slightly. After about six months of laying eggs, her feet, toes, claws and shanks will also fade. When she quits laying, you will see the color come back to these. This is kind of interesting to me since the bright color of her cone and wattles is a surefire sign that she is laying or about to. When she stops laying she will turn pale pink. It seems just the opposite from her other body parts.

Deformed Chicken Eggs and Egg Abnormalities

The most bizarre of the deformed chicken eggs that I’ve ever found in my flock is the shell-less egg. It doesn’t happen often, but every once in a while, I get a chicken laying soft eggs. As you can see in the photo, it’s perfectly formed down to the protective membrane, but the shell simply didn’t form around the egg. If you reach into the nest for your eggs without looking, it’s a pretty freaky feeling to grab hold of one of these. These types of deformed chicken eggs usually happen in a chicken that is just beginning to lay. I have only had this happen four or five times in all my years of owning chickens.

If you have more than one of these deformed chicken eggs, or find them frequently, be sure you your chicken feed offers a balanced diet and add calcium. Be sure to not eat this egg. You can give it to your dogs or hogs, but not to humans. Since the protective shell didn’t form, it’s very probable that bacteria has gotten through the membrane contaminating the egg.


Another big abnormality is the double yolk eggs. I have to say in my 30-plus years of chicken keeping, I’ve had less than 10 of these. These don’t really count as deformed chicken eggs. This photo was taken a long time ago. I remember taking it because it was the first one I had received from my girls in years and I didn’t know when I would have another one. The double yolked egg is just an egg that has developed two yolks. Kinda like it wanted to be twins! This egg is perfectly safe to eat.


Your eggs may be weirdly shaped. You may have an outcropping on your eggshell. This is just a little extra deposit of calcium like you can see in this photo. Interesting “swirlies” often form in the shell making process.




Even though I’ve never had one, I’ve heard of having an egg inside an egg. This is caused when an egg gets backed up for some reason and goes through the last production stages twice.

I had this egg from one of my younger hens. It was such a puzzle to me. The egg is cracked almost all the way around, yet the protective coating (called the bloom) sealed the egg.


Not a true abnormality, but worth noting, is blood around the yoke. It’s considered a hereditary characteristic in some chicken breeds. Blood in chicken eggs isn’t an indication of fertilization. This kind of egg is completely edible. If you have a rooster, you may notice a white or slightly discolored spec in your yolk when you crack your egg. Congratulations! You have a fertile egg and given the right opportunity it would’ve become a chick. This egg is edible, which is a good thing because almost all my eggs are fertile. Yep, my guys are on the job. As you can see in this photo, this was the shell-less egg. I cooked it for the dogs.


Of course, if you crack an egg and it smells funny, don’t eat it! It’s good to know how to perform an egg freshness test when in doubt. One of my grossest memories is when I was helping my grandmother, and I use the term “helping” loosely, fix breakfast. She had fried the bacon, which came from their smokehouse and was cooking eggs. She had fried two or three and reached for another. When she cracked it open and plopped it into the hot skillet, there was a half-developed baby chick! Oh boy did it stink! Needless to say, she rushed it out the back door then cleaned the skillet. I remember she said, “That’s what I get for not cracking it into a bowl first.”  She had to explain to me that she had found a nest of eggs and thought she had tested them all for freshness, but that when you’re not sure, you should crack the egg into a bowl first and then use it. She couldn’t have taught me a more memorable lesson. As you can imagine, neither one of us had eggs for breakfast.

What is the most abnormal egg you’ve had in your flock? Have you experienced any of these? I really enjoy that no two eggs are exactly the same. I can tell which breed laid which egg, but not which hen. Can you tell?

Originally published in 2015 and regularly vetted for accuracy.

  • I get the occasional micro egg. Usually a little bigger then my thumbnail.

  • I have several eggs that look perfect when cracked in the bowl, but after a few seconds the yolk breaks! Is this a deficiency of some kind? How is it corrected?

  • Doris C.

    I started out with 4 different breeds, each giving a differet color egg. The Black Australorp laid what I called torpedo eggs, long and not what you’d call egg shaped. they have since become very pretty eggs. I did get one with no shell and it was a wierd feeling egg for sure. I now have 2 different blues, 2 different browns and 1 green egg for the hens.

    • Rhonda C.

      Doris, I bet your egg basket looks like Easter every day! What a great color scheme 🙂 Thanks for sharing!

  • I have had almost all of these in my years of owning chickens.
    I have never had an egg inside an egg or a blood egg. I have had double yolkers, soft eggs and eggs with extra deposits. The first time i had chickens I had 1 isa brown and the rest bantam silkies and pekins. I never had a soft egg or double yolker from the bantams. But I had them with the isa brown. In the first 6 months of henny penny (the isa brown) laying she laid about 3 soft eggs and 2 double yolkers. Then in the next year she probably laid only 1 more soft egg and another 2 double yolkers. Then I went a period of 2 years were I didn’t own any chickens. Then when we were on a suitable property we bought a new flock, all pekins and 1 silkie. I’ve had all these hens from point of lay or chicks and I’ve finally got 1 double yolker from a pekin. I still haven’t had any soft eggs which is a good thing right? Anyway it’s really funny I have almost all the same breed yet their eggs differ so much. The silkie has a very elongated egg with a slighty dark colour. My black speckled pekin had a very round egg with a slightly dark colour. My buff girls have identitcle eggs, normal shape and very light. And my millefeur pekin girl has a very round egg with a lighter colour. when bantam eggs are full size they are about half the size of an average egg. When my girls first started laying the egg was about the size of a large grape. But I wouldn’t call those a micro egg so I’m almost excited to get some layer hens and get a micro egg cause they seem really amazing!

  • I found, what, I don’t know… a gross, black, bloody, spongie egg? blood clot?? Cut it open and it oozed out a yolk? The outer part was thick /black/spongie, looked burned. What is it? Don’t know how to send pictures of it. Anyone????

  • I’m not sure which hen it is but one of my ladies lays eggs with swirl patterns in the shell every day. Some days they are gentle ripples, some days the egg is covered with ridges. One time the egg was coarse with the deep ripples like it was carved from sandstone. I’ve seen maybe 3 or 4 of the shellless eggs. It seems to happen to my Black Copper Marans as they start laying (which is also latter than my other breeds). One of my Americauna lays a double yolk fairly often. I’ve seen an egg inside an egg one time. I also have a hen who lays eggs with paper thin shells. They are fine but can easily break in the nest or when washing. It seems like most of the really weird stuff happens early in the spring, especially if they stopped laying over the winter.

    • Hi! I have a chicken (hen) that lays the rippled groovy eggs. They are called “body checked” eggs. They are safe to eat. Just weird looking! Look up “body checked” to get more info and photos!

  • As I was frying my egg, I went to turn it over and the yoke rolled right off of the egg white. I continued to flip the egg white and then tried to flip the yoke which busted. I still ate it. Any idea what causes that? It was so weird.

  • This is my first time time òwñing chicken’s. I have 6 isa browns who are 21 weeks old, oñe of them is laying small brown eggs. Yesterday I got a soft shell egg. Is it a lack of calcium or a beginning of làýiñg? Thank you, great article!

  • I recently cracked open an egg and found a pebble almost the size of a pea in the whites. Gross!

  • Well I still don’t know what causes deformed eggs. You should title your article descriptions of deformed eggs. You offered little if any cause for any on those you described.

  • We have had eggs laid that are hollow. That means No egg white or yolk, only shell. What would cause that?

  • We have 12 hens of various breeds. I am not sure who lays this type egg, but we get ones that are a darker brown, about the size of a large grape with no yolk inside, just egg white. Every so often it shows up in the coop. We also call them micro eggs, but it is funny that there is no yolk. I’m not sure why this happens, but they seem fine otherwise!

  • The part about fertilized eggs having a white spot is not quite true. Most eggs have white spots. Fertilized eggs have a spot that resembles a doughnut. Eggs can and will have a white spot even without the presence of a rooster.

  • One of my girls started laying big soft-shelled eggs in her 2nd year. They get good quality later feed, green house oyster shell, and even occasional cheese and yogurt treats. Everybody else’s eggs are fine. Anyone else have luck correcting this problem, or do I just have a messy, no-goood-for eggs pet on my hands?

  • I’ve been getting eggs for about the last 4 months and I get 3-4 double yokes every week. I save those for the kids. They think it is cool.

  • I grew up with hens in North Wales – farm hens, backyard hens, garden hens – and, now, in the south of France, my wife and I have had two hens for the last 18 months, since they were at point-of-lay. They are more pets than anything else. They are both good layers, and each of their eggs is recognisably identifiable.

    One, Roussette, a mad girl at the best of times, often lays eggs that are in some way or other eccentric, but I can usually recognise the oddity from my younger days, and these variations tend to fit in with the descriptions in this helpful article. (Thanks Rhonda.) The other, calmer girl, Brunette (I wanted to call them Aur a Brown, but that was ruled out by Management), has until recently laid perfectly calm, regular eggs. But now she is laying eggs that look more like flattened pebbles from a river bed, are not a uniform colour and have slightly rippled shells, a bit like what you call ‘swirlies’. These eggs look perfectly fine when opened and when eaten boiled, my usual pleasure, they are as good as ever.

    Today, after a short period of neither of them laying, which I think is just a response to some severe winter weather here, they have both laid again, but have both laid these ‘pebble eggs’. I can’t think that they have any serious problems with their diet, they are well housed, and Brunette began laying her ‘pebbles’ long before the weather deteriorated. Any comments would be most welcome. Many thanks and all the best, Paul

  • Shirley S.

    I found what seemed like a “water balloon” egg. The shell was so soft it felt like a balloon but when opened it was a full egg with white and yolk. Currently I am getting an elongated, light pink egg from somebody. It is so long it won’t fit in an egg carton but seems like perfectly good egg. I only have 4 hens that are almost 2 years old. Lots of fun having a backyard flock.

  • I get eggs often that look as if they cracked while still in the chicken and then she sealed it up with an extra layer of shell before laying it…almost like she bandaged it up…lol.

  • Today I picked up 2 soft shelled eggs, laid over night. I say 2 but they were clearly laid as one as they had flat sides where they would have been together. I’d like to send a photo but not sure how to. I have 4 spring chick, all laying well. One has laid several ( 5 or 6 in 3 months ) double yokers, they are Very large, her record to date is 98 grams! Anyone else experienced this 2 egg phenomenon?

  • Beverly R.

    One chicken is repeatedly laying shell-less eggs. However, I have given this bird oyster shell supplement, but she won’t eat oyster shell. What should I do to remedy this problem?

  • Catherene C.

    I have a larger mixed flock of 70 hens, pulleys, chicks, a cockerel, 7 roosters (1 banty, 6 standard) plus 2 drakes and 4 duck hens in 3 pens, was 4 but I integrated a couple after rehoming a few roosters. I get one wrinkled egg on a near daily (6-7 days) basis but can’t find the layer of it. She either lays early before I’m up or mid-afternoon when I’m gone. The shells are a little tougher to crack but the contents are good. None of the possible hens are over 18 months old. I also have gotten shellless eggs with individual
    membranes around the white and yolks, one of my ducks laid 2 of these in a row a few months ago (tossed them). I get ones with sealed cracks at times. I sell eggs so we keep these for ourselves or to give away. We have very rude neighbor’s about 1/8 mile away that feel the need to share their choice of music with everyone in a mile radius (heard from neighbors that far away that could hear it too). It’s not an all day long, it nearly every day for hours on end, nothing police can do due to laws or lack of. The noise definitely affects my chickens egg laying process and quantity – no loud noise and I get lots of well formed eggs, so called music blasting – fewer eggs and more deformed ones. They are just ignorant people that don’t care. There’s 3 other small farms that are closer and they have similar problems with eggs too.

  • I’ve only had chickens for 1.5 years and I’ve already experienced nearly all of these! I wish I could submit a picture because my Easter Egger laid a green egg with another fully formed (though smaller) egg inside it! It was fascinating!!! I made sure to take a few pics because I doubt I’ll have another. I felt bad for her that day because the egg was HUGE!

  • We get double egg yolked eggs fairly frequently from one of our hens for a couple months. We also had an egg that looked like it had a knot tied in the bottom of it, it was very cool.


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What Causes Deformed Chicken Eggs and Other Egg Abnormalities?