An order of ectoproct bryozoans (in which the anus opens outside the ring of tentacles) in the class Gymnolaemata. Cheilostomes possess delicate colonies composed of loosely grouped, highly complex, short, uncurved, box- or vase-shaped zooecia (chamber in which the animal lives), with solid, porous, chitinous, or calcareous walls, and with apertures closed by lidlike opercula.