I went into my coop this morning and found this black egg right in the middle on the ground! I only have 3 types of chickens and i thought they all layed white or brown eggs. The kinds I have are Rhode Island Red, Black Australopes and Buff Orpington's. Is this a sign of a sick chicken?? I recently got my chickens a couple months ago 95% of them aren't laying only one of them is so far, so i dont understand why this one is big and black!!