any member of the class Stenolaemata, a group of colonial marine animals within the invertebrate phylum Bryozoa (moss animals). About 900 species of stenolaemates have been described. Only one of the four orders that make up the class, the Cyclostomata, is represented by living species; all members of the other three orders (Cystoporata, Trepostomata, and Cryptostomata) are now extinct. The stenolaemates are the oldest of all the bryozoans and date from the Early Ordovician Epoch (505 to 478 million years ago) on. The individuals (zooids) that make up a stenolaemate colony have narrow, cylindrical, sometimes very elongated tubes with calcified walls.

Crisia eburnea, found in tide pools on both coasts of North America, grows on algae and seaweed and forms white bushy tufts about 1.25 to 2.5 cm (0.5 to 1 inch) high.