Horn corals are from the extinct order of corals called rugose. They grow in a long cone shape like a bull’s horn. The fossil is the skeleton of the coral animal or polyp. The animal lived in the top of the cone. As the animal grew larger, more CaCO3 material was added to the top of the cone. While modern corals are colonial, the now extinct horn corals could be either colonial or solitary animals. The animal had many tentacles from the body to gather food which gave them a flower-like appearance. The oldest of the rugose corals can be found in rocks from the Ordovician Period. Many species evolved during the Paleozoic Era. As a group, they flourished until the Permian Period when they went to extinction along with most living things during the great Permian Extinction.
horn corals, rugose