Smallest living organism

The smallest entity universally recognised to be a living organism (not everyone considers the slightly smaller nanobes to be alive) is Nanoarchaeum equitans. This minuscule microbe was only discovered in 2002, in a hydrothermal vent on the seafloor off the coast of Iceland, and its cells are only 400 nanometres across. In addition, its genome is only 490,885 nucleotide bases long, which makes it the smallest non-viral genome ever sequenced.