Form large colonies with tubes that are constructed of fine sand and cemented together by the worm. The short tentacles of the worm are lavender. The worms have an operculum that can close off the tube. The diameter of tubes is to about 12 mm. The colonies are at least to 2 m across. If the tentacles are a beige color and covering is golden when closed then it is Sabellaria cementarium.

Honeycomb in design, they form on or against rocks and particularly in areas where there is high sand movement.

Intertidal to 72 m; Central California to Baja California, Mexico.