These diatoms lack raphes and have elongated, narrow frustules visible in both valve and girdle views. They form ribbon-like colonies, with cells connected side by side through small interlocking spines at the valve edges, although these are not discernible with a light microscope. These ribbons are often attached to submerged plant surfaces.n the girdle view, the cells have an oblong shape with a swelling at the center. The cells link together to create a ribbon-like colony. The valves are symmetrical and feature transverse striae. They are linear and elliptical, with rounded edges. Frequently, there is a gap between each cell on each side of the swollen center. Each cell contains two large chloroplasts.