Sea anemones are colorful marine animals that belong to the phylum Cnidaria. They are closely related to jellyfish and coral. Sea anemones have a soft, cylindrical body topped with tentacles that contain stinging cells called nematocysts. These tentacles help them capture prey, such as small fish and plankton. Sea anemones are often found attached to rocks or coral reefs in shallow waters. They can vary in size and color, ranging from a few centimeters to over a meter in diameter. Some species have a symbiotic relationship with clownfish, which provide protection in exchange for food and shelter.