Photomicrograph of a diatom from stratum2B. Diatoms are microscopic, single-celled photosynthetic algae with silica cell walls. This is Epithemia turgida, the most common diatom species in the bench deposits. An aquatic diatom, it has a wide range of environmental tolerance and can live in shallow, stagnant water. Source: Brown (2006:Fig. 7.15).