Hexagonaria percarinata Coral.jpg

Hexagonaria percarinata Coral

SITE LOCATION: Michigan
TIME PERIOD: Devonian Period (359-419 million years ago)
Data: A Petoskey stone is a rock and a fossil, often pebble-shaped, that is composed of a fossilized rugose coral, Hexagonaria percarinata.  Such stones were formed as a result of glaciation, in which sheets of ice plucked stones from the bedrock, grinding off their rough edges and depositing them in the northwestern (and some in the northeastern) portion of Michigan's lower peninsula. In those same areas of Michigan, complete fossilized coral colony heads can be found in the source rocks for the Petoskey stones. Petoskey stones are found in the Gravel Point Formation of the Traverse Group. They are fragments of a coral reef that was originally deposited during the Devonian period.
Kingdom: Animalia
Phylum: Cnidaria
Class: Anthozoa
Order: †Stauriida
Family: †Disphyllidae
Genus: †Hexagonaria
Species: †percarinata