Horn Coral, Devonian Aged From New York

Here is an associated of two pieces of horn coral and an enrolled Eldredgeops rana rana trilobite from the Windom Shale of NY. The trilobite appears to have been found separately and mounted onto the matrix for display. It's Devonian in age, or approximately 385 million years old.

Horn coral or Rugose coral first appeared in the geological record 488 million years ago and went extinct during the create Permian extinction 251 million years ago. They get their name from the hornlike structures built by the coral animal. They are very often used as an index fossil to help correlate the geological age of different formations.