Michigan’s state stone is a colony coral that lived in a warm Devonian sea here 350 million years ago, and it turns up as smooth grey cobbles all along the northern Lake Michigan shore, showing its six-sided cell pattern the moment it is wet. Petoskey State Park and the beaches from Charlevoix to Traverse are the classic ground; hunt the wet line after a storm. PUBLIC beaches: Michigan allows collecting up to 25 pounds a year of rock and mineral from state land, but NOT from national lakeshores such as Sleeping Bear.
Fossil coral (Hexagonaria)
See it on the map
Other places on the map within a couple of hours.
