Because they have a soft body, coral secreates calcium carbonate, or limestone for protection. Coral Polyps are only the size of a pin head. Sometimes they are mistaken for plants. When zillons of coral live together they form a coral reef.
Coral is found in all the oceans of the world.
It grows best in clear water where there is sunlight. Reef-building coral need warm ocean water. Coral colonies only grow 0.5 to 4 inches a year, and may live for several decades to centuries. Coral eat zooplankton. They use their tentacles to capture their food.