The « Left-Handed Neptune » is a peculiar buccinid that is normally sinistral or coiled left-handed, hence the name. An eastern Atlantic to Mediterranean species, it ranges from Spain to Portugal to Morocco. It inhabits a rather wide bathymetric range of around -100~800m deep and is known to live deeper in the southern part of its range. It is a comm.on carnivorous gastropod throughout its range. Although generally little-varied and cannot be mistaken with any other species, it is greatly variable in size. Typical shell length is around 100mm., but very large individuals may attain 190mm. The colouration is also variable and ranges from white to dark brown. Two well-known synonyms include perversus Kiener, 1840 and sinistrorsus Deshayes, 1832, both also refer to the reverse-coiling characteristic in this species.

Along the shelf and upper continental slope from the southern parts of the Bay of Biscay to Morocco (Locard, 1897) in 100—1000 m. Mediterranean records seem to be based on fossil specimens (Barsotti & Frilli, 1970).