W. Ireland & Channel Islands to Angola & offshore islands, Mediterranean & Black Sea. Lives in tubular structures made of cemented debris, or in sedimentary rocks, large shells, coralligen, from subtidal grounds to circa 50m deep. Eight-shaped orifices.

« Gastrochaena pholadia: this shell is enclosed in a testaceous, irregular, claviform tube, situate at its broader extremity; it is open and attenuated anteriorly, with an oblong, bilobate aperture, which is nearly subdivided by a projecting septum that does not quite reach across the opening; these serve for the passage of the two tubes of the animal; the posterior end of the tube is closed. This club-shaped tube is found either within the perforated cavities of rocks, or in old shells or corals, the testaceous tube always protruding beyond the surface. […] an extremely local species. » – T. Brown: Illustrations of the recent conchology of Great Britain and Ireland, London 1844, via BHL.

« The body is claviform, broad anteriorly, tapering posteriorly, the siphonal tube capable of considerable extension. The mantle is entirely closed, with the exception of a small aperture in front, for the passage of the small finger-shaped pointed foot, which has a byssal groove at its base. » – Forbes & Hanley: op. cit. vol. I, p.134-135.

The species can nest not only in various rocky substrates but also in rapidly growing Bivalves such as Ostrea edulis or Pinna nobilis, in the colonies of the coralline alga Lithophyllum stictiforme, the yellow coral Leptopsammia pruvoti and the white coral Cladocora caespitosa; also, but more rarely, in slow-growing thick Bivalves such as Venus verrucosa and Glycymeris nummaria (DORIS).