The Archean Eon lasted from 4 to 2.5 billion years ago and is a significant period in Earth's history, marked by the formation of continents, the emergence of the first life forms, and a dramatically different atmosphere than today's. It's a time when Earth transitioned from a molten state to one with a more stable crust, oceans, and the beginnings of a biological world.
During the Archean Eon, which lasted from about 4.0 to 2.5 billion years ago, life was exclusively microbial. There's no evidence of animals, which are multicellular, nucleated organisms, during this time. Instead, the Archean eon saw the rise of single-celled organisms like bacteria and archaea, with the earliest evidence of life being prokaryotic microbes.