I found this while digging up arrowheads today. I'm in Illinois. It was about a foot below the surface. Its was found with some native American flint pieces
It's about 5 inches long
It looks more like a very large skeleton key with the piece at the very tip broken off.
When old iron decomposes in the ground it attracts everything in close proximity to it and forms a crust... It's like a junk magnet