Calcite, silica and other minerals have replaced the original elements in each cell. Each chamber or corallite at one time was a living marine animal that grew in colonies. The Petoskey stone is also known as a colony coral. The Petoskey stone can be found in Michigan from the shores of Traverse City across the state to Alpena. It can be found in gravel pits, on road beds, and mainly on the shores of Lake Michigan around the Petoskey area.
Early spring is a good time to look for the stone after the ice has melted along the shore.
During the summer months the best time to look for the stone is after a wind storm or during a mist rain when the stones will show the fossil pattern more clearly. The eye of the stone is seen as the sun, and the lines or tentacles are seen as the rays radiating from the sun. The stone was named Petoskey because of the abundance of them found on the shores of Little Traverse Bay. In 1965 the State of Michigan adopted the Petoskey stone as Michigan's state stone. Its six sided pattern will allow you to identify it from other fossils.