Species in this group can be distinguished by being tall and slender, with heavy costae and a strong basal disk. This one has been found in water at a depth of at least 1000m in the eastern Atlantic, from Portugal to the Canary Islands and the Azores. In the western Atlantic, it was found off Culebra Island, Puerto Rico. It reaches a maximum size of approximately 5mm. C acus is ivory-white in color and has about 8 teleoconch whorls. There are about 17 heavy costae. It can be separated from some other species in the group by the absence of spiral sculpture. A basal disk is present. The aperture is oval and there are 3 brown protoconch whorls. Minute pits are present on the teleoconch whorls.