What is Fossil Coral?
TOP Corals are part of a group of animals called Cnidaria (nid-AIR-ee-a), also called Coelenterata (sel-EN-ter-AH-ta), which includes sea anemones, corals, jellyfish, and hydras. All of these animals are soft bodied and have multiple arms or tentacles, with which they grab food from the surrounding sea water. All Cnidaria (including corals) live in water and most are marine animals. The soft, jelly-like body of an individual cnidarian animal is called a polyp. Coral polyps secrete a rock-like skeleton of calcium carbonate around them. Calcium carbonate is also the dominant consituent of the rock, limestone. Because modern corals live in large colonies, these skeletons can become quite large, sometimes forming reefs. When the polyp dies, its soft tissue decays, but the hard skeleton is left behind. The hard skeleton of ancient corals is what is preserved as a fossil. All modern corals belong to the order Scleractinia (SCLER-ac-TIN-ee-a). In the past, fossils indicate that there were two