This afternoon I was cleaning out the nesting box in my backyard coop. When I opened the main door to the coop something strange fell out. It was kind of like a paper-thin eggshell, with nothing inside of it, slightly crumpled like it had been shut in a book. I did lose a chicken last week - I thought she was egg-bound, but now I'm wondering if she had an egg break inside of her? Anyone ever have anything like this?