I've bought this as a coprolite a long time ago. I don't have an exact location, but the person I bought it from dives costal rivers in the Southeast United States. Something about this one always seemed a little weird. As I have been re-photographing my coprolites, I discovered one specimen in my collection that was actually a tilly bone. It had been mounted in a plastic display case, so I had never looked at the bottom. The composition of this seems similar to that specimen. But I do have true coprolites that also have that surface texture. I know at one time I thought this might be a cololite or a steinkern of some sort, but that didn't seem quite right either. What do you all think? The bottom view is the one that I thought might be diagnostic. Thanks for looking!