Cylindrotheca cells are solitary and are characteristically needle-like, thin and elongated in shape. The ends of the cell tend to be drawn out from the center part. The frustules are only lightly silicified. The valves, including the keel and raphe canal, wrap around each other, forming a twisted frustule. As a result of the strong twist of the raphe system, the cells rotate and twirl as they move. The girdle bands are narrow and numerous.