Maybe it was a part of the hen's chalus (maybe spelled that wrong) that an egg was forming around that got swallowed up by a regular egg on the way down? Did you crack open the smaller one to see what was inside of it?
I found this old thread about an egg inside of an egg.
Thread 'Hen Laid An Egg Inside Of Another Egg' https://www.backyardchickens.com/threads/hen-laid-an-egg-inside-of-another-egg.1298369/
We got rain here last night. It soaked into the dry ground, but there's water standing in the bottom of my bucket by the back porch.
That looks like a partially developed egg inside of the egg. It happens sometimes.
Maybe what parts you ate growing up might have something to do with it? My parents always bought the whole chicken. They got the breast. I got the thighs, brother got the drumstick, and my sister loved the wings. I look at the wings as being a waste. I debone the cooked wings now and let the dog...
No, I let those go so that I could make room for the leghorns. I didn't want to mix the 2 breeds, and prefer working with one breed at a time. I've found that I'm mostly out for the egg's and not the meat. Meat is good, but I don't want to be sending them to freezer camp too frequently, and the...
They are good roosters. They are good to the hens, and the best thing was that I didn't have to worry about them attacking me in there. I have changed over to doing the non-white leghorns now though.
That's very true.
That is true also. There is no guarantee on shipped egg's hatching, especially when you don't know how the sender will be packing them, or how they will be treated in traveling to the destination.