A marine or freshwater, colonial invertebrate belonging to the Phylum Bryozoa; many are characterized by branching mineralized exoskeletons from which multiple individuals (zooids) extend from small pores to filter feed using crowns of tentacles (lophophores). Bryozoans have a long and exemplary fossil record and are especially common in Paleozoic (540 to 250 million year old) rocks. One of the more common Paleozoic varieties looks like fine-mesh cloth with numerous tiny holes in which the individual animals in the colony lived (see image on the left). Although they function somewhat like coral, and are often found in similar environments, bryozoans are more closely related to brachiopods. Image on right side shows what bryozoans look like up at high magnification, under a scanning electron microscope.
