Shell pupoid, oval-conical quite solid, translucent, adult reaches 2.2 mm in height and 1.1 mm in width with somewhat more than three teleoconch whorls. Profile of the spire flat-convex. Entire surface furrowed by spiral cords wider than the interspaces and crossed by conspicuous axial ribs, somewhat opisthocline, similar in width to the interspaces, disappearing in the basal part of the body whorl. The upper cord forms a narrow subsutural rim. Suture slightly canaliculated and a typical suprasutural depression characteristic of Crisilla. Aperture oval, somewhat narrower at the upper part. Outer lip thickened with denticular folds internally. Yellowish background colour of the shell with two rows of reddish spots, the upper one sub-sutural. A reddish border of the inner lip is also seen.
Protoconch multispiral, with 2.25 whorls and about 420 µm in diameter. It seems somewhat eroded in the specimens studied, but some rows of small granules aligned in at the end of the protoconch II can be seen ending into three irregular lines.

This new species is the third of the genus Crisilla known to have a multispiral protoconch. These three species show a more or less gradual transition between Crisilla species and those of one of the lineages currently ascribed to Alvania, being C. transitoria an intermediate link. This new species differs from C semistriata and C. transitoria by its slightly smaller size, stronger sculpture and slightly opisthocline axial ribs. We include it in the genus Crisilla because it presents the characteristic pair of subsutural furrows. While C. transitoria has a wide geographical distribution in West African coasts, C. monicae , despite having a multispiral protoconch (indicating a planktotrophic larval development and consequently a potential high dispersal capacity) has only been found from one locality of the Gulf of Guinea.

Only known from empty shells found in the type locality (Miamia, Ghana).