DC has a very good idea, it really could be a broken piece of a bucket tooth. If the trees in the area don't look 200yrs old then the place was logged at one time and bucket teeth haven't changed much since the days of steam machinery.
Another thing. Have you cleaned the center area of it. It looks good for a old piece of metal. I not saying it's not old. There appears to be some marking on it. I'm working on a piece of thick metal similar to yours. It's not from a piece of equipment. The teeth are made different. The edges are clean like it was made that way. Metal.that is torn or broken off well look jagged.