My buddy brought this to work today to see if I could help him answer this very question about an oddly shaped stone he found in a delivery of driveway stone. I had no measuring device so used the cd edge to give you an idea of length. What do you folks think?
I looked at the enlarged view of both sides. At first I thought it was the beginning of a pipe, but the back is contoured as well.
Don't know what kind of tool, but I do think its a tool.