The Petoskey stone, found only on Lake Michigan along the northwest coast of Michigan, is Michigan's state stone. They are fossilized ancient coral. i have many Petoskey stones, gathered when I was growing up near Petoskey
The Petoskey stone was born as coral approximately 400 million years ago, when a shallow sea covered Michigan. Over time, the coral fossilized and now washes up on beaches and peeks through road grades across Northwest Michigan. - Nature Is Beautiful
Petoskey Stones were formed by the fossilization of ancient coral, Hexagonaria. The coral lived in shallow waters. Petoskey Stones are found on many beaches of Lake Michigan and Lake Huron. Petoskey stones, only found in Michigan.
A Petoskey stone .is a rock and a fossil, often pebble-shaped, that is composed of a fossilized coral that lived 350 million years ago. The rocks rounded in the surf along the shores of Lake Michigan near Petoskey, Michigan.