An order of marine invertebrates (order: Hydrazoa), members of the phylum Cnidaria which also includes jellyfish (order: Scyphozoa), and corals and sea anemones (class: Anthozoa).
An order of marine invertebrates (order: Hydrazoa), members of the phylum Cnidaria which also includes jellyfish (order: Scyphozoa), and corals and sea anemones (class: Anthozoa).