Native Ethnic Stone Tool Cylinder Shape Oval Knife Sharpener Gray HELP ? America  OLD.  Good to very good condition.  HELP.  What is this?  My grandmother had this piece in her antiques store and it was some type of native ethnic tool.  Any help would be appreciated.

A nice ebayer has told us this....
My best guess is that it was used as a pestle for grinding herbs, medicine, etc. It also may have been used to chip arrow heads but based on the fine burnishing on the end I'm thinking more likely as a pestle

2 3/4 by 3/4".  Well worn very old rock/stone.

Shelf:  #ddd