How Was The Petoskey Stone Formed?
So, what is a Petoskey stone? It is a fossil colonial coral that lived in the warm Michigan seas during the Devonian time around 350 million years ago. The name Hexagonaria (meaning six sides) percarinata was designated by Dr. Edwin Stumm in 1969 because of his extensive knowledge of fossils. This type of fossil is found only in the rock strata called the Gravel Point Formation. This formation is part of the Traverse Group of the Devonian Age. During the Devonian time, Michigan was quite different. Geographically, what is now Michigan was near the equator. A warm shallow sea covered the State. This warm, sunny sea was an ideal habitat for marine life. A Devonian reef had sheltered clams, cephalopods, corals, crinoids, trilobites, fish, and many other life forms. The soft living tissue of the coral was called a polyp. At the center of this was the area where food was taken in, or the mouth. This dark spot, or eye, has been filled with mud of silt that petrified after falling into the op
