Petoskey stones are unique fossilized coral found along the shores of Lake Michigan in Petoskey, Michigan. They are composed of the fossilized remains of coral from the Devonian period, around 350 million years ago. When polished, these stones reveal a distinctive pattern of hexagonal shapes, making them popular among collectors and jewelry makers. These stones are typically gray or brown and can vary in size. The best time to find Petoskey stones is after storms when the waves wash them ashore. They are not only a natural treasure but also the state stone of Michigan, symbolizing the region's geological history.