Shell translucent, semitransparent, whorls not much convex, conic in form. The most important characteristic is the aperture small, pyriform. False suture evident, visible as one line white in colour. Last whorl, rather roundish, is little less than half of total height. Lip oblique that, whether seen laterally, seems it is inflated, without one sinus. Columella vertical, as high as about half of aperture, no siphonal canal. As it can be seen through its transparent shell, the animal is red orange in colour. In the lower part juvenile specimens have a lip more expanded and last whorl less rounded. The adult specimens average measures are around 3.5-4 mm but there is a sexual dimorphism. Usually the female is bigger.

Shell conical, almost straight in profile, small, completely transparent, without ornamentation or coloured zones. The transparency fades with the fixation, although it is maintained in those preserved dried. In these, the sutures and growth scars are well observed. Teleoconch whorls flat and slightly convex at the protoconch. Last whorl quite high, occupying almost half of the height of the shell. In the dry specimens, the suture and false suture are clearly distinct. Both are parallel, the space between them quite narrow and more opaque in appearance than the rest of the shell.
The growth scars are not aligned, located at a different place in each whorl. There are growth periods in which the animal almost form a complete whorl, while in others only a half whorl is formed. The scars appearing irregularly. The SEM photographs show the surface of the shell totally smooth, without any kind of microsculpture, except the sutures and growth scars. These scars are strongly marked and located irregularly in the different whorls.
Apex slightly sharpened. Protoconch with 2 whorls faintly convex, transparent, whitout ornamentation or colour that differentiates it from the teloconch. There is no mark indicating the existence of protoconch II, and therefore this species might lack a planktotrophic larval phase. No microsculpture is appreciated in the protoconch.
Aperture wide, round and slightly sharpened at its upper margin. It is quite low and faintly surpasses the edge of the lower part of the shell. In lateral view, the inner lip presents the first section straight coinciding with the zone between the sutures; then projected forming a sinus, very marked at the centre. Inner lip with columelar callus very patent, located at the lower margin of the aperture, coinciding with the base of the columella. Size: The size (length/width) of the specimens from Tenerife ranged from 0.45/0.31 mm in an specimen with one whorl to 1.85/0.79 mm in other of 6 whorls.
Soft parts: Soft parts orange-brown, clearly observed by shell transparency. Several yellowish spots are observed in the gonad-visceral zone and other reddish stand out on an orange back¬ground. These spots do not seem to follow a constant colour pattern. In the suture of the last whorl a reddish spot is appreciated, diffused and edges scarcely defined. At the sides of the head there are also small reddish zones. Cephalic tentacles very long, slender, sharpened and almost transparent, with faint yellow highlights on the surface, mainly on the apical zone. Eyes black and large, placed quite close and slightly behind with respect to the tentacles. At the base of each eye a more intense orange spot is observed. Vision by transparency through the shell. Foot also orange. Operculum very thin, transparent, oval, with faint growth lines. Animal capable of complete retraction inside the shell. Radula absent.

Common in a large part of the Mediterranean where it has a remarkable bathymetric diffusion: from a few tens of metres up to remarkable depths, usually in a coralligenous habitat. It lives as a parasite on sea-urchins of Cidaroida order (Cidaris cidaris).

It was only known from Malta, Sicily and Gulf of Naples. We recorded it here for the first time in the Atlantic ocean. Engl (com. pers.) has found this species in sediments coming from the CANCAP expeditions, and Templado (com. pers.) has found a quite similar species (probably the same) in Cape Verde Islands parasiting the Cidarid Eucidaris tribuloides. MiFSUD (1990) found several specimens of this species (cited as Eulima nana) adhered to the largest spines of the sea urchin Cidaris cidaris. The same year, WAREN AND MIFSUD (1990) erected the new genus Nanobalcis to embrace a group of small eulimids parasitic on cidaroid sea urchins, and designed E. nana as type species of this genus. They recorded this species from Malta and the Gulf of Naples. Until now this species has not been recorded outside of the Mediterranean Sea.