I've been finding strange evidence of an egg eater in the coop. I find what appears to be the membrane liner and stains in the wood shavings that look like yolk/white. But not a trace of eggshell. It is always in the coop under the roosting bars, so far we've never found such in the nest boxes. I have 5 young pullets that just started laying a few weeks ago. I'm hoping I don't have to search out the culprit and cull her. Any suggestions?