Brain corals are actually colonial animals. They can create mounds 6 to 8 feet in diameter, and play an important role in reef construction. Endosymbiotic algae within its cells gives the coral its green color.

The symbiotic relationship is so efficient in recycling minerals between the plant and animal that it gives brain corals a dominant evolutionary advantage: they grow more quickly. Collectively they are known as hermatypic corals (from the Greek god Hermes, speedy messenger).