I found either a rock or a fossilized bone in NW Arkansas along the War Eagle River earlier this year. The War Eagle Quadrangle https://core.ac.uk/download/pdf/72842749.pdf has sections that are Ordovician, Devonian, and Mississippian.
That being said...is this just a rock? I don't want to state why I think it might be one thing or another....needing a fresh perspective.