It looks like a rib bone to me... Take a look at the ends - if it looks like lots of small holes, it's bone and that's the marrow area. Could be fossilized - I have some deer antler bases that are fossilized and are about the same color and totally mineralized
Some more photos would definitely help from these it looks like a piece of stoneware to me with a little bit of salt glaze left not earthenware I would expect from Native American pottery
About positive it's not bone or tooth, will have to get some better pics or get it in someone's hands with experience in pottery. It is clay and shaped by hand I'm pretty sure, just don't know how old it may bebe.
What kind of context was it found in? What other items have you found in the same area? Is there any other info that could narrow down the possibilities or at least make more probabilities in one direction or another?