Posted by ROSHAN B.S on Aug. 26, 2014, 9:16 p.m.
Single-celled microorganisms were the first forms of life to develop on Earth, approximately 3–4 billion years ago.[13][14][15] Further evolution was slow,[16] and for about 3 billion years in the Precambrian eon, all organisms were microscopic.[17] So, for most of the history of life on Earth the only forms of life were microorganisms.[18] Bacteria, algae and fungi have been identified in amber that is 220 million years old, which shows that the morphology of microorganisms has changed little since the Triassic period.[19] The newly discovered biological role played by nickel, however — especially that engendered by volcanic eruptions from the Siberian Traps (site of the modern city of Norilsk) — is thought to have accelerated the evolution of methanogens towards the end of the Permian–Triassic extinction event.[20]