speaking of oyster shell, mine have it available at all times and some of my eggs have white dots all over them,some uniform some not. someone loves their calcium a bit too much. can this hurt them?I dunno... I have had egg eaters.... they usually EAT, so everything is cleaned up, just tiny little left overs.
So, I don't think you have an egg eater... I think it got stepped on.
I sometimes get eggs that aren't as strong as I would like. Dunno why... they have oyster shell