I have noticed egg yolk on the bottom of the coop for a few weeks and had been blaming a hen for egg eating. I separated the hens to try to determine which hen. I have witnessed all three hens jump on an egg laid outside the nest box . Now the weird part. I came home to find one hen fluffed out wings out to her side and looking funny. I went to pick her up to examine her and an egg actual shot out and hit the coop wall !!!!! It's not an exaggeration! It splattered and they all ran to gobble it up. I can add grit , but what caused it to be expelled like that?