Unusual Artifact/Stone Tool? Looking for ID

[swizzle]

Found this by the mohawk river a while back. Just found it going through my rocks again and it got me wondering if Its a naturally occurring rock or a stone tool. One side has quite a nice polish on it. Its not bone. I've had a few people ask if it was a jaw bone. Its definitely stone.

 

[OZARKS]

Doesn't look worked, appears to have been created by water

Having said that, I'm no stone expert...lol

 

[lookingharder]

Neat rock. I was an expert in my field for 30 years... then I sold the farm and moved to town.

 

[Treasure_Hunter]

Looks natural water erosion.