Thanks, Den in Penn. Yes, this happened to my sweet girl this morning.
I always help her down. Am waiting till my handyman gets back next week to redesign the coop. The step I built to help them up and down from their 4' high shelf where they love to sleep at night doesn't work. They use it to go up but not to go down, and it was going down I built it for, to help prevent bumblefoot. Instead, they just fly over it going down.
Alas, my big girl always slept in the nesting box until we built the step. Then she discovered she loved the shelf. How I wish we'd never built the step. She gets up to the shelf but can't get down, so I've been getting up early and going out and lifting her down manually. She was always last. The lighter girls fly off first. I was waiting for them to come down this morning, when I hear this thud onto the pine shavings, and it was the fat girl, trying her wings. I couldn't believe it. If I'd only been watching more closely I could have saved her that fall, but I stand outside trying to see where their feet land. One girl landed on a wooden piece and I was afraid it could cause bumblefoot.
My fat girl picked herself up and seemed fine. She seemed to have hit her breast, so I didn't think the egg would be broken. She had good energy and ate well this morning, but at about 1 or so I went out to the run and found her egg in the middle of it. Very unusual. And with the cracked side. There were like puzzle pieces of the shell broken/smashed, but not off the egg, and no yolk leaking. Only one eensy piece of shell was missing.
It is possible that she could have laid the egg on the potting bench and it rolled off, but she's never done this before. Unless it just fell out when she was up there? I did have a hen drop an egg early one morning.
A few weeks ago she did lay an egg in her nesting box that attached itself to her tailfeathers via poop, I think, and she carried it a good distance that way, into the greenhouse run, without it falling off her. When it finally fell off her, though, it didn't break. She has strong shells on her eggs and eats a lot of laying mash. That may be her salvation, I hope. So for this one to be broken, something must have happened...
I suppose it could have fallen out of her and another chicken could have stepped on it, but not likely. I think it must have cracked inside her when she fell, and for some reason that trauma caused the egg to be expelled several hours later.
I'm worried that the rough side of the egg with the cracked shell bits could have scraped her internally coming out, even if those shell bits didn't come off or get stuck inside her. Could the egg have abrazed her innards, I wonder?