| Gregarious fanworm
| Operculate fanworm
Permanent tube-dwelling polychaete; body length from 5–7 cm with up to 200 segments. Head possesses two opposing circles of bipinnate radioles, forming a spiral crown when extended outside of its tube, and a calcareous operculum that is funnel-shaped and pinkish white in color. Tube is cylindrical with some irregular ridges and is made of calcium carbonate. Body can be pale yellow to red in color.
Constructs calcareous tubes on hard substrata such as rocks, stones, and bivalve shells. Found from sublittoral fringe to circalittoral up to 250 m depth. In some very sheltered areas, the tubes aggregate together to form small reefs.
Tubes are permanently attached to the substrate. Can be gregarious if there are few substrates for larvae to settle on, but in open marine habitat, it is usually solitary
Active suspension feeder, exposing its bipinnated crown out of its tube to feed. The pinnules of the radioles create water current into crown, which collects suspended material from the water column.