Most of our corals that grow in the Pacific Ocean need sunlight to live. Coral grow algae within their polyps and they need sunshine to survive. The algae gives the coral its green, brown, blue or yellow colors.
Cup corals on the other hand grow in dark areas where the sun does not shine. They are similar to an upside down jellyfish living in a hard tube attached to the reef. These little corals catch small organisms floating in the sea with their stinging tentacles. They are usually bright orange, pink or red.
They are animals, not plants and when the surf is big or person gets to close to them they retract into their hard tube for protection. The only way to see these beautiful creatures is to dive down and peek into a cave with an underwater light!
Aloha,
Terry