Anthozoan is a term used to describe a group of marine creatures that includes corals, sea anemones, and their relatives. There are several synonyms and related terms that can be used to describe these animals, including cnidarians, polyps, and sessile invertebrates. Cnidarians are a group of invertebrates that includes anthozoans, jellyfish, and other organisms that possess stinging cells called nematocysts. Polyps are a type of anthozoan that typically live attached to the sea floor, while their free-living counterparts are known as medusae. Sessile invertebrates are organisms that are permanently attached to a surface and cannot move on their own.