Giant Cup Mushroom Coral

It is a large coral with diameter around 20cm. They form in small groups in shallow coral reef areas. A single individual has many thin and short tentacles that appear on the oral disc, but are not seen on the rim. The coral can contract a circular muscle on the perimeter of the wall of its body to transform to a pouch-like structure. Its colors are dark reddish-brown, greenish brown, and green.