Petoskey stone is a rock, often pebble-shaped, that is composed of a fossilized coral called Hexagonaria percarinata.
Petoskey stones are fragments of a coral reef that was originally deposited during the Devonian period, about 350 million years ago. When dry the stone resembles ordinary limestone but when wet or polished the distinctive hexagonal pattern of the fossil appears. It is sometimes made into decorative objects.
Petoskey Stones can be found on various beaches in Northern Michigan with many of the most popular being those surrounding Petoskey and Charlevoix.
Polished and prepared stones can often be found at gift stores in the Petoskey area.
In 1965, it was named the state stone of Michigan.
For more information about Petoskey stones try these links: