CentralNotice From Wikipedia, the free encyclopedia Jump to: navigation , search For a molecule of two atoms, see Diatomic molecule . Diatoms Marine diatoms Scientific classification Domain: Eukaryota (unranked): Sar Phylum: Heterokontophyta Class: Bacillariophyceae Dangeard , 1933 [ 1 ] Synonyms Diatomea Dumortier , 1821 [ 2 ] Diatomophyceae Rabenhorst , 1864 [ 3 ] Bacillariae Haeckel, 1878 [ 4 ] Bacillariophyta Engler & Gilg , 1919 [ 5 ] Diatoms [ 6 ] are a major group of algae , and are among the most common types of phytoplankton . Diatoms are unicellular , although they can form colonies in the shape of filaments or ribbons (e.g. Fragilaria ), fans (e.g. Meridion ), zigzags (e.g. Tabellaria ), or stars (e.g. Asterionella ). The first diatom formally described in scientific literature, the colonial Bacillaria paradoxa , was f...