Unusual in the family of corals, this species -Halomitra Pileus- is a free-living coral, thin and delicate, and circular, sometimes dome or bell-shaped. I means they are not attached to the ground. Colonies can be large, covering extensive areas of horizontal substrate. They are Pale brown, frequently with bright pink or purple margins especially at night when they feed. But their skeletton is a perfect white! This piece is a very large one.