Turbonilla is a large genus of ectoparasitic sea snails, marine gastropod molluscs in the family Pyramidellidae, the pyrams and their allies.

The generally slender, bluish-white to milk-white, semitranslucent shell is more or less elongated and has a cylindro-conic shape.

The reversed, flattened or projecting protoconch consists of 1½ to 3 whorls that are oblique or tilted from transverse to the axis.

The intercostal spaces are smooth or crossed bv more or less distinct, incised, sometimes raised, spiral lines.

The spiral lines often also appear on the base of the shell, which varies from short, little rounded (the body whorl is subangulated at the periphery), to elongate and well-rounded.