Pandoravirus sediments. Pandoraviruses, like other marine viruses, prey on plankton, which are organisms that live in the water column and form the basis of the food chain for other marine species. More study and research needs to be done in order to confirm the prevalence of Pandoraviruses in different environments. Currently, not much is known about their role in marine ecosystems. Pandoraviruses do have approximately 93% of their genes that are unidentifiable with any other microbes, suggesting they may belong to an as of yet undescribed "fourth domain" aside from Bacteria, Archaea, and Eukaryotes. Viruses as a whole are not popularly
Microbial mat the causes, cyanobacteria are the most self-sufficient of the mat organisms and were well-adapted to strike out on their own both as floating mats and as the first of the phytoplankton, which forms the basis of most marine food chains. The time at which eukaryotes first appeared is still uncertain: there is reasonable evidence that fossils dated between and represent eukaryotes, but the presence of steranes in Australian shales may indicate that eukaryotes were present . There is still debate about the origins of eukaryotes, and many of the theories focus on the idea that a bacterium first became an