Polyp

Coral reefs are made of connecting polyps, forming a colony.  Polyps are small soft-bodied organisms made of calcium. Their base is a durable, protective skeleton. They are nocturnal and closed in the day unless there is a food source. Polyps also contain algae called zooxanthellae, which gives the polyp amazing colors. The front of the polyp has a center mouth surrounded by stinging tentacles used to catch zooplankton. The polyp is hardy and easy to care for in the home aquarium if provided with its basic needs.