They formed colonies with robust, calcified exoskeletons, allowing for a high potential for fossil preservation.

Stenolaemates were the predominant bryozoan group during the Paleozoic, when many extinct orders proliferated within the class.

[3] Some grew as lacy or fan-like colonies that became important reef builders, and in some regions form an abundant component of limestones.

[5] However, the basal and previously rare stenolaemate order Cyclostomatida diversified in the Jurassic and became the most abundant group of bryozoans in the late Mesozoic.

Cyclostomatida is no longer the most speciose bryozoan group, as the order experienced high rates of extinction during the end-Cretaceous mass extinction, while ctenostome and cheilostome bryozoans in the class Gymnolaemata diversified around the same time.