Interesting, Kinsey. My sweet girl who laid the egg was a Barred Rock. I wonder whether the disease associated with it is the peritonitis? That is what I would suspect. But, like I said, my girl only laid one such egg, as far as I know, unless she laid some in spots I didn't find. How old is your girl who lays the similar eggs? I think this egg got stuck in my girl for a while and she just dropped it early the next morning, rather than actually laying it, because I found it much earlier in the morning than the girls normally laid. She may have been too fat, and that may have interfered with her egg-laying and maybe killed her. I have suspected fatty liver disease, but never got a diagnosis of any kind, as she died while I was away on vacation.