Healthy hens, primarily on there younger years, will occasionally lay a misshapen egg here and there but not on a frequent basis. In this post, I will explain some of the causes of Smashed-in eggs (which are also called slab-Sided eggs) and White-banded eggs…
Slab-Sided egg (as pictured above):
The Main Causes: Drastic lighting changes, Over-crowding and/or stress. Slab-sided eggs can also be an indicator of illness but I have had perfectly healthy hens in my flock lay them so a one time occurrence is nothing to be overly concerned of.
How it happens:
When two eggs enter the shell gland pouch (one shortly after the other), the second egg, being not as complete as the first, flattens on the side where the two eggs make contact.
White Banded Eggs
White-Banded eggs (pictured below) are caused by the same thing as slab sided eggs (eggs coming into contact with one another). However, the reason that the result varies is because the calcification process that is interrupted by egg shell contact, resulting in a ring of calcium.
Above picture borrowed from BackYardChickens.com