What is a polyp in the sea?

A polyp is a sessile (attached to a surface) cnidarian, typically having a cylindrical body and a ring of tentacles at one end. Polyps are the asexual phase in the life cycle of some coelenterates, including jellyfish, corals, sea anemones, and hydroids. They can reproduce asexually by budding or by binary fission, forming colonies of genetically identical individuals. Polyps are also sessile (usually attached to a substrate) and may form large colonies, particularly in coral reefs.