One of my girls has started pooping jet black poo. Shape and texture are normal, but it is solid black. At first I thought someone had tossed a couple of black olives in the run. I have looked at all the poop pics I can find, but none have solid black. Nobody seems sick, all three girls are eating, drinking, and acting completely normal. Any ideas? Should I be worried? This is not blackish, or black/white, but is dark, jet black. Thanks for your help!