I have an aging black hen whom was having problems with her egg shells about a month ago. The small end would come out looking like sand paper, and I mean the rough grit sand paper. At that time they seemed to be rather small if I remember correctly. I've been feeding free choice oyster shell for about a month now, and the "sand paper" texture of the eggs have greatly diminished. They are smooth all over now and are 100% better than what they were. However this evening, I picked an egg out of the coop and it was nearly 3/4 the size of a standard egg. It filled almost my entire palm. Can oystershell actually INCREASE the size of eggs laid by a hen?