The fertilized egges in some bryozoans in the class Stenolaemata divide so that up to one hundred identical eggs are brooded at a time in specialized zooids. There is great diversity in the types of bryozoan larva, some feed, some are flattened, some have a shell, some are zooid-like, but all form a ciliated, free-swimming larva for some length of time, then settle and undergo dramatic reorganization to reach their mature form.
A bryozoan colony begins with an ancestrula (the primary zooid), which is formed sexually. The colony then grows by asexual budding, in a pattern dictated by the particular taxon. Bryozoan colonies are found in a wide array of colony formations. Encrusting forms (most common) can cover large areas of rocks, algae, shells or exoskeletons of other invertebrates, ship hulls, and other hard substrates. Other forms include arboristic, branching, discus, amorphous blob shapes or (especially in freshwater taxa) the zooids can grow as buds along a cord-like stolon. There is one genus of mobile bryozoans, Cristatella, which, in the shape of a caterpillar, crawls along substrates at very slow speed! Some freshwater taxa also form new colonies by asexually producing statoblasts, which drop to the bottom if the parent colony does not survive and survive harsh conditions in a dormant mode. The statoblast then generates a new zooid when conditions are more optimal. (Brusca and Brusca 2003; Kozloff 1990)