Coral reefs have been around for more than a billion years. For A long time coral was thought to be a plant. But in 1723 they were to be proposed as animals by naturalist Jean Andre’ Peyssonel. He was immediately expelled from the French Academy of Sciences. Today, we know that coral belongs to a group of animals called Cnidarians, which are little round animals with tentacles around their mouth. Only in the South Pacific, so far over 700 species have been discovered. One coral across measures around ½ of an inch. But together they can build the largest things on Earth: Coral Reefs. Coral reefs are actually made up of mostly the skeletal remains of the coral polyps. Polyps constantly reproduce and survive atop of their fellow polyp’s skeleton.