These cells contain numerous small chloroplasts, and their setae project perpendicular to the pervalvar axis. They can be found as individual cells or in short chains, with a diameter ranging from 5 to 20 µm. Typically, they are observed individually or in very short chains. When viewed in water mounts, the cells often present an oval or round shape in valve view, with a flat valve surface. When seen from the side (girdle view), there is a narrow gap between adjacent cells. The setae originate at the margin of the valve, and they are long, rigid, and oriented perpendicular to the pervalvar axis.