I have 4 cornish hens, all perfectly healthy, but today I went inside their house to find what looked like the membrane of an egg all over the floor under one of the perches.I looked around for pieces of a shell to see if maybe they pecked an egg open but there was nothing. Looks like one of the hens layed a membrane with no shell or anything. I almost thought it was pee or something, but chickens don't pee. any suggestions on how or why it happened?