I think one of my hens, who hasn't started laying yet (I think), "laid" a yolk. I found it, slightly opaque cover, no egg white, no shell/s in the nesting area. My one hen who is laying just came out of the coop, did a short egg song, but no egg there. Does this happen on occasion to a hen who's laying good eggs on a daily basis? All of her eggs have had a nice hard shell so far. So not sure if Sarah laid it, or one of the other 2 who hadn't started laying yet? Any ideas???