Rock Stone Hole Fire starter Fire Starter Nutting Stone Paleo Found Native For Sale

Found on private property in Arkansas. Honestly, I\'m not sure if this is a rock that is very hard because it has iron in it or if it\'s some sort of slag but I find it quite often and it always has some sort of design or a hole or bowl shape. If you buy this rock and figure out what kind of rock this is please let me know. I\'ve wondered for years. It seems very hard but also always smooth on the edges as if very worn, thanks so much.