Wister OK

[MSirmon]

Found this item while digging around after some heavy rains eroded some channels down the hill directly behind the cabin near Wister Lake. This area is Pennsylvanian in age. Any ideas?

[caldigger]

Perhaps a sponge of sorts.  Way out of my further IDing league though.

[Rockwood]

It looks like bone to me. Perhaps a worn centrum.

Small ones like that would have evolved by then. I think.