A favosites is a type of extinct coral. Favosites coral fossils most identifying feature is the honeycomb-like openings (coralites) revealing where the animal (polyps) lived. The polyp tentacles could tuck inside for safety, typically at night, or stretch out from their calcium-carbonate substrates in order to filter tiny food particles floating by in ocean currents.

The large fossil sample shown first is preserved in sedimentary claystone. It was found in a field in the city limits of Saugatuck, Michigan, part of the Ellsworth-Antrim Geological Formation (Mississippian-Devonian), Allegan County, Southwestern Michigan, USA. This particular type of honeycomb coral fossil is more commonly found in Charlevoix, Michigan, situated in the Traverse Group Geological Formations in the far northeastern region of the state. Consequently, they’re often called, Charlevoix Stones.

The tabulae (horizontal internal layers) place the favosites corals in the order of tabulata with internal chambers that built outward and upwards as the organism grew.

Diagram of Favosites Internal Structure

The walls between corallites were pierced by pores known as mural pores which allowed transfer of nutrients between polyps as illustrated below.

Like all coral, favosites corals thrived in warm, shallow, sunlit seas. They were a colony type coral forming colorful quilt-work reefs and fed by filtering microscopic plankton with their stinging tentacles. They were most prevalent during the Silurian and Devonian time slots, but date as far back as the Ordovician and forward to the Permian between 251-488 mya. That’s over 200 million years of living on earth . . . amazing!  

Favosites Classification

Common Name: Honeycomb Coral        Scientific Name: Favosites 

Kingdom: Animal

Phylum: Cnidaria (means to sting)

Class: Anthozoa (means flower animal)

Order:  Tabulata (possess inner horizontal dividing walls)

Family: Favositidae (honeycomb pattern on exoskeleton)

Genus: Favosites Species: Alpenensis (Charlevoix Stone)

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