This is a “pitted” or “nutting” stone, used as a nutcracker or grinder. Nuts or seeds would be placed in the depression and then cracked or ground with a small round stone used as a hammer or grinder. This particular stone has pits on both sides. Other items such as pigments, plants, and berries were ground for use in medicinal remedies, dyes, and pigments. Native people used these for many thousands of years from about 6,000 to 300 years ago.