River bones...?

[Further]

These were all found in the same river, over time. It is a river in SE Texas known for fossil finds from large mammals in the Pleistocene. I think due to their river tumbling they are not identifiable, but I just wanted to see if it is possible they could be some type on mineral rather than bones? Pics are front back. We find a lot of petrified wood in the area too, but it normally looks distinct from this.

The two on the left almost look like they are variations of the same thing, and the one second from left has some kind of almost enamelish looking stuff in threads on the surface. None are metallic, a magnet does not stick and my metal detector does not beep going over them. The one in center with all the layers I would normally ID as some kind of tooth, as I have seen that before. Any thoughts would be appreicated.

[Rockwood]

Sorry. I think these are all some type of mineral and not bone.