What could be wrong to cause this egg?

[aart]

Feed dates are hidden on the tags where I get my feed.

All manufacturers have different systems...some are not readable by the buyer.
I use Purina Flock Raiser and it's very obvious what the mfg date is.

 

[Ebony Rose]

Some hens won’t eat them. I have a hen that struggles with calcium and she freaking REFUSES to eat the oyster shells. It’s ridiculous XD.

An excellent alternative is to feed back crushed egg shell. Most hens love to get this!