5.8" Polished Slab Petoskey Stone Hexagonaria Coral Fossil Devonian Age Michigan
Location: Michigan, United States
Weight: 2.9 Ounces
Dimensions: 5.8 Inches Long, 1.6 Inches Wide, 0.3 Inches Thick
The item pictured is the one you will receive.
Devonian Age, 350 million years old
Petoskey Stones are remarkable fossils, representing the ancient rugose coral Hexagonaria percarinata. Usually pebble-shaped, these stones are primarily found in the northwestern and northeastern parts of Michigan's Lower Peninsula. They are remnants of a Devonian-period coral reef, dating back approximately 350 million years, offering a rare glimpse into the marine ecosystems of that era.
Petoskey stones were formed during glacial periods, when ice sheets plucked rocks from bedrock, smoothing rough edges and depositing them in specific areas. When dry, these stones appear as ordinary limestone, but when wet or polished, they reveal a distinctive mottled pattern of fossilized corals.
The fossils belong to Hexagonaria percarinata, an extinct colonial coral composed of tightly packed, six-sided corallites—the skeletal structures of once-living coral polyps. Each corallite’s center contained the polyp’s mouth and tentacles, used to capture food. The hexagonal shape of each cell, along with the thin radial lines extending from the dark central “eye”, are unique identifying features of this fossil coral.
Petoskey stones can be found on various beaches and inland locations in Michigan, with many of the most popular Petoskey stone beaches stretching from Traverse City to Petoskey along Lake Michigan. The movement of the frozen lake ice during the winters is thought to expose new stones each spring. Popular locations for finding these stones include Petoskey State Park, Magnus City Park Beach, and Solanus Mission Beach. Rockhounds also search cut roadbeds, gravel pits, and farmers' fields. The best time to find them is often in the spring after the ice has shifted the shoreline.
