Bugula flabellata is an erect bryozoan that forms low dense tufts, between 2 – 3 cm in height. The colonies are made up of a number of fan-shaped shoots that are dichotomously divided into flat wedge-shaped branches, broadening at the tip. The branches are arranged in a somewhat circular manner and often slightly convoluted. When living the colony is of a buffish colour, but turns grey when dried.
The species almost invariably attaches to other bryozoans. Even when it is apparently growing on rock or shell, closer examination usually shows the exact site of attachment to be some species of encrusting cheilostomate bryozoan. Bryozoan species commonly supporting colonies of B. flabellata include Porella concinna, Schizomavella auriculata, Schizomavella linearis, Cellepora pumicosa, fronds of Flustra foliacea and lobes of Alcyonidium diaphanum. Small modified zooids which resemble rootlets (rhizoids) are used to attach to the colony to the substrate. The species often occurs as a co-dominant with Chartella papyracea in communities colonizing vertical shaded, sublittoral rock surfaces in the Bristol Channel.
Bugula flabellata is relatively common on the lower intertidal area of rocky shores, extending down to shallow inshore waters. The species apparently has a wide geographic distribution and occurs throughout the North Sea and off all British coasts. The species appears to be a successful fowler, and its arrival and spread has been recorded in New Zealand ports. On the east coast of America, Bugula simplex was long mistaken for Bugula flabellata.