I have one Black Australorp hen who is consistently laying eggs with clusters of tiny calcific nodules on the shell. These look just like the eggs I see on the underside of leaves in my garden where bugs have laid eggs. These are hard and seem to be made of the same materials as the shell its self. They don't rub off or even scrape off easily. Each nodule is half the size of a pin head and discrete from the others nearby. Any help??