Hexagonaria

Name Meaning: Six Sided One

Location Found: Michigan

Geologic Era: Devonian

Size: Roughly 2 centimeters in diameter (on average for this specimen)

Estimated Range: Modern Midwestern United States

Extinction: End Devonian

This is a Petoskey Stone, or the state stone of Michigan. They are relatively common across the state and a good part of the Midwest as well. Hexagonaria was a type of coral, specifically the rugose type. This type of coral is no longer in our oceans, as the last rugose corals went extinct toward the end of the Permian era. Rugose corals could be either solitary or colonial, which is in contrast to modern corals, which are entirely colonial. Rugose corals like Hexagonaria were considered micropredators, meaning they were eating microorganisms as opposed to larger animals. These specimens are somewhat easy to obtain, though the true shape of the coral does not become apparent until the specimen is polished (as ours is).