i have a chicken that has started laying eggs with no shell. two weeks ago , i noticed the insides of the egg in the coup near the nest boxes. no shell or evidence of a shell. and no real yolk , just the white part of the egg. today, i see the actual egg with a paper thin (thick enough to hold the insides together, but thin enough to see thru it). shell. the entire egg is intact. i have a mixture of 13 americana chickens. 7 hens are almost 2 years...the other 6 have just started laying. i can account for all the newbies and 5 of the older hens. with that said, 1 older hen doesnt produce (not sure which one, still pinpointing between 2). i am sure it is an older one but i do not know why she is doing this. help? i do not give them any extra oyster shell , but i do make sure they get dried crushed shells and i try and make sure that all the chickens get plenty.