Sabellaria spinulosa reefs or crusts will form on hard substratum but this does not preclude their formation from other substrata (Hiscock 1991). Rees & Dare (1993) describe habitat preference as being typically on shell (especially oyster valves), sandy gravel or rocky substrates with moderate tidal flow. Larsonneur (1994) reported Sabellaria spinulosa-dominated communities present on rock/pebble bottoms in the Bay of Mont St. Michael. It is likely that stability of the reefs is to some degree a function of the stability of the substratum. The more transient crusts probably occur principally on relatively unstable substrata, while longer-lasting reefs could be limited to more stable substrata.

Dense reefs reported in the Bristol Channel were found at a depth of 41m (George & Warwick 1985), while recently discovered reefs off the north Norfolk coast were found at 15-25 m (Foster-Smith et al., in prep. February 1998).