Horn Coral is a type of Rugose Coral, named for its hornlike
shape. Rugose corals belong to the order Rugosa and were named for their wrinkled (rugose) appearance.
Horn corals such as this one are known to have reached over a meter in length. Some other types of
rugose corals were colonial.
This much smaller specimen came in an $8 fossil kit. It was difficult to get good
focus on it because of its shape.
It was collected in Texas and is listed as being from the Pennsylvanian.