(sigh-new-ra) is a synurophyte alga, traditionally regarded as a chrysophyte or related to the chrysophytes, but distinguished by the presence of extracellular siliceous scales. This genus is one in which many cells are joined together to form a swimming spherical colony. Each cell has two large chlorophyll a and c containing plastids, two emergent flagella, and a coating of flattened scales. This image is a detail showing the scales of the periplast . Differential interference contrast.