If you’re a fan of classic acts such as Bob Seger or Mitch Ryder, you know that in Michigan, they love to rock.
Also, they love to collect rocks — in particular, the Petoskey stone, the official state rock. The latter is found on the state’s beaches and sand dunes, where Michigan residents and visitors often collect it as a souvenir, because it has a striking hexagon pattern embedded in its surface that can be brought out with polishing.
The Petoskey has that feature because in addition to being a rock, it’s also a fossil — a remnant of coral that lived in Michigan during the Devonian Period, 350 million years ago. (The hexagon is actually the ancient animal’s mouth.)
Given all that, you can understand how utterly cool it must have been for rock hunter Tim O’Brien of Copenish, Mich., to find a 93-pound Petoskey stone in Lake Michigan, near the town of Northport.

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