We have 10 (buffs, rhode island reds and plymouths) twenty wks old. I feed them grain, growth, and laying pellets. So far we have gotten 7 eggs that are very small (like bantams would lay). We suspect the same hen may be the layer since they all look alike. However we did get one darker one that is more the size of a goose egg. Today we got one small egg this am and another small one this afternoon which it only has a skin cover... No shell! They are all well fed. We are new at this. Any help will be appreciated.