The cells contain one chloroplast and are organized into single chains forming spiral shaped colonies. The thin setae lacking chloroplasts are crossing slightly outside the chain edge creating rectangular windows. All setae are bent in one direction. Resting spores have one valve with two humps and setae continue into the parent cell setae.
Apical axis measures 8-40 µm.
Throndsen, J., Hasle, G.R. and Tangen, K., 2007. Phytoplankton of Norwegian coastal waters. Almater Forlag AS. 341 pp.