Sea anemones are marine animals that belong to the phylum Cnidaria, which also includes jellyfish and coral. They have a soft, cylindrical body topped with a ring of tentacles that contain stinging cells called nematocysts. These tentacles help them capture prey, such as small fish and plankton, and provide protection from predators. Sea anemones are often found attached to rocks or coral reefs in shallow waters. They come in various colors and sizes, and some species can live for many years. Many sea anemones have a symbiotic relationship with clownfish, which provide them with food scraps and protection in return for shelter.