海葵, known as "sea anemone" in English, is a marine animal belonging to the phylum Cnidaria. These creatures are often found attached to rocks or coral reefs in oceans around the world. They have a soft, cylindrical body and are characterized by their colorful tentacles, which contain stinging cells used for capturing prey and defending against predators. Sea anemones have a symbiotic relationship with certain species of clownfish. The clownfish find protection among the anemone's tentacles, while the anemone benefits from the nutrients provided by the fish. This mutualistic relationship is a fascinating example of cooperation in marine ecosystems.