4.3" Polished Slab Petoskey Stone Hexagonaria Coral Fossil Devonian Age Michigan
Location: Michigan, United States
Weight: 2.1 Ounces
Dimensions: 4.3 Inches Long, 1.4 Inches Wide, 0.4 Inches Thick
The item pictured is the one you will receive.
Devonian Age, 350 million years old
Petoskey Stones are unique rocks and fossils, specifically the fossilized rugose coral Hexagonaria percarinata. Typically pebble-shaped, these stones are found mainly in the northwestern and northeastern regions of Michigan's Lower Peninsula. They are remnants of a coral reef that thrived during the Devonian period, approximately 350 million years ago, preserving intricate structures of ancient marine life.
The formation of Petoskey stones is closely tied to glacial activity. Ice sheets plucked stones from the bedrock, smoothing rough edges and depositing them in new locations. When dry, these stones may resemble ordinary limestone, but when wet or polished, they reveal a distinctive mottled pattern of six-sided coral fossils. Each Hexagonaria percarinata fossil consists of tightly packed, six-sided corallites, the skeletal remains of once-living coral polyps. The center of each polyp housed the mouth, with tentacles extending outward to capture food. The hexagonal shape and thin radial lines emanating from the dark central “eye” are unique features that make Petoskey stones instantly recognizable.
Petoskey stones can be found on various beaches and inland locations throughout Michigan. Many of the most popular beaches stretch from Traverse City to Petoskey along Lake Michigan, where the movement of frozen lake ice during winter exposes new stones each spring. Well-known locations include Petoskey State Park, Magnus City Park Beach, and Solanus Mission Beach. Rockhounds also search roadbeds, gravel pits, and farmers’ fields for these treasures. The best time to find Petoskey stones is typically in spring, after the ice has shifted the shoreline, revealing fresh specimens.
