Lophopus; fixed and stained individuals showing their complex structure. Lophopus is a type of Bryozoan, which is a common inhabitant of freshwater and shallow seas. They are tiny (.5mm), and occur in sessile colonies with exoskeletons of chitin, protein and calcium carbonate. They are hermaphroditic, with internal fertilization and brood chambers. Their embryo produces a larva which settles and forms a new colony.