in michigan near the grand river..rock highly unlikely..at first i thought it might be some type of cutting tool because it looks almost like its been worked into a sharp edge but after hours of looking at it i kind of ruled that out because it just dosent seem sharp enough..ive seen many indian artifacts and it dosent look to be worked as many of the cutting tools ive found .to me it looks like some sort of carnavor tooth.. by the way it would be faceing back...if it was in a mouth...i could be wrong tho