General description (after 223 shells from 16 localities). — The shell is rather long, slender and, since the top is more pointed than in most other Chrysallida, conical. The protoconch is of type B, strongly tending to A (planorboid or Al); a part of the first half whorl is visible. There are five to seven teleoconch whorls; the upper 2/3 of these whorls is straight, the lower part is convex, because it is bent strongly inwards to the suture, which is open, deep and oblique. The ribs are about as broad as the interstices, in almost vertical position. They are somewhat undulating on the last whorl, curved or nearly straight on the initial ones. The last whorl has three (occasionally four) spiral ridges. Two of these, situated at some distance above the upper edge of the aperture, are pronounced, almost as broad as the ribs. The third ridge is on the same level of the upper side of the aperture, the occasional fourth spiral ridge at some distance below. In most shells the ribs continue to the third spiral, sometimes just to the second one, sometimes, decreasing into lines, they continue almost to the base of the shell. The initial whorls have two pronounced spiral ridges on the periphery. All these spirals run over the ribs, forming tubercles on the crossings. The aperture is small, rhomboid. There is no tooth, occasionally an insignificant umbilical slit.
Length 2.4-3.8 mm, LW 37-48%, A 19-25%, L/B 2.8-4.1, B/b 1.2-1.5 (based on 18 shells).

Because of its characteristic shape, C. fenestrata cannot easily be confused with any other Chrysallida but, on the contrary, it looks like Turbonilla, by its tall, slender, pointed appearance and the absence of a tooth. However, the protoconch of a Chrysallida disappears more into the first teleoconch whorl, and there is no Turbonilla with such pronounced spiral ridges as C. fenestrata has.

From the Mediterranean (rare in the central and more eastern parts) north to the British Isles. Also known from Mauretania (NNM).