Shaped Petoskey Stone Pendant. This particular stone is a little larger and shows off a lot of multi-colored hexagon cells. The Petoskey stone (Hexagonaria Percarinata) is the state stone of Michigan, and found primarily in the lower peninsula of Michigan. It is 350 million year old extinct fossilized coral. Each handmade Petoskey stone pendant on this website is found by Greg, slab cut, shaped, and polished by hand in 6 steps with very fine sandpaper until they reach their maximum shine. They vary in color, cell shape, and size. No two are the same. They are a beautiful stone, and ALWAYS the attention getter in the room! Consider purchasing a 925 Sterling Silver Chain with this item.