Odostomia conoidea: Shell: to 5 mm, milky white, almost opaque; very smooth and polished, with a glossy surface. Usually with a narrow spiral incision around the periphery of the body whorl. Protoconch partly submerged in first postlarval whorl. Umbilicus usually a narrow chink, but in large specimens a deep hollow. Tooth strong and prominent. Often, but not always, with spiral ridges on inside of outer lip. Soft parts: Mentum deeply cleft and diverging. Eyes small and close together. The front of the foot strongly ciliated. Pigmented mantle organ (hard to see clearly through the shell) elongated, almost linear, reddish yellow, with numerous small, yellow-white spots in a row above the gland. Operculum: of same type as 0. acuta (underside not studied).

Odostomia conoidea: Usually found at intermediate depths, from 50-60 to 200 m. According to Fretter et al. (1986) usually in association with the starfish Astropecten irregularis. "Food. Presumably the starfish" This needs verification, as echinoderms are not among the usual hosts for pyramidellids.

Habitat: it lives in the infralittoral and circalittoral zones.
Distribution: it can be found all over the Mediterranean. It is the most common species of its genus, sometimes collected into gastric contents of starfishes found off Castiglione della Pescaia (Grosseto - Tuscany -Italy), at 80 m depth.
Notes: this species belongs to subgenus Megastomia Monterosato, 1884 (=Stomega Dall & Bartsch, 1904) owing to a series of denti¬form folds, visible in transparence too from external surface, in the internal part of external lip. Shell solid, conic in form but variable in outline. Whorls are either flat-sided or not much convex, suture broad, often caniculated. Umbilicus quite evident with columellar tooth broad. Outline of last whorl is usually rounded but as far as specimens of deep water are concerned it is angulated due to the presence of a carina at the periphery. Growth lines orthocline. Protoconch type A, that is with external nucleus. Always white dull in colour. Measures of adult specimens are really variable: the shell can reach 7 mm in height too and it is one of the largest species of this genus.

Distinctive features:
• Shells with a clear tooth on the columella.
• Shell surface smooth or with spiral striature. No (spiral) ribs.
• Inside of the outer lip with a series of list-like teeth.
• Shells white, growthlines vertical.
• Topwhorls helicoid (type A).

Odostomia conoidea: Best identified by the combination of the partly submerged protoconch (nucleus partly hidden by first postlarval whorl) and the spiral incision around the periphery of each whorl, in addition to the solid, glossy shell.

Odostomia conoidea: Some think that this species is sufficiently different from Odostomia plicata to be placed in another genus. This is supported by the molecular analysis of Schander et al. (2003). In this analysis 0. conoidea is (following van Aartsen) placed in the (sub)genus Megastomia at the outset, a decision they find to be supported by their molecular data. There is however no convincing reason to put it in the nominal genus Megastomia, which is based on Odostomia conspicua which, in my opinion is a typical Odostomia s.s. and has few traits in common with 0. conoidea.

Odostomia conoidea: Distribution: In Norway reported from the southern and western coast by G.O. Sars (1878) and from the Bergen area by Norman (1879). In my material thirteen samples from Skagerrak, 29 specimens and an additional 54 shells, more or less evenly distributed north to Bindalsfjorden (c. 65°N). Further north nine specimens from around Bodo. A large (5.0 mm) specimen in Saltfjorden (67°10*N, 170-90 m, Modiolula phaseolina bottom). Outside Norway it is known from the Swedish west coast, the west and south coasts of the British Isles and Ireland and further south along the Atlantic coasts of France and Spain and the Mediterranean (Fretter et al. 1986, Peñas et al. 1996, Óztürk et al. 2013). Apparently very common in the Mediterranean, and by Óztürk et al. listed as the most abundant Odostomia distributed along the Turkish coast. By van Aartsen et al. (1998) stated to be abundant also along the coast of Mauritania and the Canary Islands.