Prenantia cheilostoma is an encrusting bryozoan that forms broadly lobate patches which are orange to reddish-purple, even when dried. Autozooids are oval to hexagonal, flat or slightly convex. They are 0.45-0.6 by 0.3-0.4 mm.
Prenantia cheilostoma is widespread throughout the Mediterranean. In the British Isles it is known from the south-west, extending north to the Isle of Man. It is frequent around the Channel Islands, but does not extend far into the eastern English Channel and is thought to be absent from the North Sea.
The species is able to colonise hard substrates, typically shell. It occurs from the shallow subtidal to offshore waters (at least 150 m).