The cup-shaped coral genus has a total of 18 species. It is a single or group animal of the Hydra type, with a body that is six fold symmetrical with two radiations. The oral wall invaginates to form an oral passage, and the endoderm of the gastric cavity wall extends centripetal to form a diaphragm. Muscles are well-developed, with cells present in the mesosphere. Reproductive cells originate from the endoderm and can form bones. Seafood, group, with bones, can be used to build reefs, and the presence of mouth channels makes its body exhibit two radiating symmetries. Having a diaphragm, the diaphragm can support increasing the digestive area. Diaphragm filaments have stinging cells, and both the inner and outer germ layers have stinging cells. Genital glands originate from the endoderm. The color is usually brown, pink, or yellow. Distributed from the Indian Ocean to the Pacific Ocean.