I feel like these may be something plant related because of the structure, small dots on the one piece, and the leaf print I see on a couple of the pieces. I found several pieces similar to these in the same area . Some are really dark and heavy/dense. Some look squared off or broken off at the bottom. They just look uncommon or unlike the other rocks found around that area. Found in a river in mid Ohio area. Any ideas ? Thanks for all your help!