Diatoms are one of the most common types of phytoplankton.

Phytoplankton are the autotrophic components of the plankton community and a key factor of oceans, seas and freshwater basins ecosystems. The name comes from the Greek words φυτόν (phyton), meaning “plant“, and πλαγκτός (planktos), meaning “wanderer” or “drifter”.^[1] Most phytoplankton are too small to be individually seen with the unaided eye. However, when present in high enough numbers, they may appear as a green discoloration of the water due to the presence of chlorophyll within their cells (although the actual color may vary with the species of phytoplankton present due to varying levels of chlorophyll or the presence of accessory pigments such asphycobiliproteins, xanthophylls, etc.).