A rainbow of colours produced from a healthy Coral Reef. Corals are actually animals (Cnidarians) related to jellyfish. Hard corals get their colour from the symbiotic algae that lives inside their polyps. The algae (zooxanthellae) provide the coral with up to 90% of its food source while the calcium carbonate skeleton of the coral provides a safe home for the algae.  The tips of coral appear white as this is the new coral growth and the algae which gives coral its colour hasn’t occupied these polyps yet.