Petoskey Stones, the state stone of Michigan, are fossilized coral resulting from glaciation and are often polished to reveal the beautiful pattern of the 6 sided coral colonies. #Geology #Petoskey_Stone #Michigan rocks
A Petoskey stone is a rock and a fossil, often pebble-shaped, that is composed of a fossilized coral, Hexagonaria percarinata. They are fragments of a coral reef that was originally deposited during the Devonian period, about 350 million years ago. (Wikipedia) Photo by Mark Willocks.