Hi there, I used to have 2 chickensthat laid those size eggs but a precautionary tale............................... One day I found in the nest box what looked like the whole of their reproductive organs . Almost as if she had prolapsed and it had come away from her body. About a month later the same thing happened to the other chicken. Neither of them ever laid another egg and eventually after about 6 months , a few weeks apart they both died.
Please do not think I am being morbid as I expect there are plenty of hens out there that lay huge eggs and are perfectly healthy but just to let people know of my personal sad experience. Beryl