Solitary or semi-colonial Hexacorallia lacking basilar muscles but usually with a flattened, adherent base. Tentacles variably arranged, simple or branched, often with sub-spherical terminal knobs (acrospheres). Column smooth, lacking vesicles, tubercles, etc. Sphincter muscle absent or weak and diffuse. Mesenteries arising in pairs, as in Actiniaria and Scleractinia, usually arranged irregularly due to asexual reproduction. Filaments lacking ciliated tracts. Cnidom consists of spirocysts, holotrichs, p- and b-mastigophores.
The only British corallimorpharian, Corynactis viridis, is easily distinguished from other anemone-like forms by its knobbed tentacles which are arranged in a distinctive manner. Most corallimorpharians reproduce by longitudinal fission and in some genera the individuals never separate completely, forming a continuous encrustation on rocks and corals.