4.4" Plate of Ordovician Graptolite Fossils - Fillmore Formation, Utah

Graptolites are tiny extinct animals that lived together in groups or colonies and shared the same skeleton. Each animal built its own living chamber, which were then stuck together to make the colony. Some colonies grew like branches of a tree, with many living chambers on each branch. Different kinds of graptolite colonies had branches with different shapes. They could be straight, curved, or even spiral-shaped.