Mediterranean and Black Sea. Grazer and deposit feeder in sheltered sandy-silty places of the upper infralittoral (2m to 30m in Locard). Introduced in southern and western Brittany, in Arcachon basin, and in Galicia, probably as stowaway during mediterranean oyster or mussel transfers.
 
Gmelin: « Shell conical, white, adorned with oblique dark flammules; whorls grooved near the suture. » (Syst. Nat., 13th ed., Tom.1 Pars.6, p.3576. – On this specimen, the dark flammules of the pattern cover almost the whole of the whitish background. 6m, on rubble bottom, Pomer, Croatia. 15mm.

« This species, at first very similar to G. magus (L.), appeared in the Basin in 1986. Its characters are as follows: solid test; maximum dimensions: 16 mm in height, 18 mm in width. Whorls 7-8, separated by a large subsutural plateau, thus forming stair steps in side view. Deep sutures. Last whorl carinated. 4 spiral cords per whorl, bearing rather marked tubercles. Base slightly convex, with 7 smooth, circular cords. Shallow umbilicus, with white callus. Sharp labrum. Large subquadrangular aperture. Whitish color with irregular brown spots and flammules. » – Bachelet & al.: “Nouvelles signalisations de Mollusques dans le Bassin d’Arcachon”, Cahiers de Biologie Marine vol. 31, Roscoff 1990.