Anemones are marine animals belonging to the phylum Cnidaria, closely related to corals and jellyfish. They typically have a cylindrical body topped with a crown of tentacles that contain specialized cells called nematocysts, which help capture prey. Anemones are often found in shallow waters and can form symbiotic relationships with other marine species, such as clownfish, which provide protection and nutrients in exchange for shelter. They exhibit a wide range of colors and shapes, contributing to the diversity of marine ecosystems.