An article published in the journal “Nature” describes the discovery of new microorganisms that provide more information on the evolution of eukaryotic organisms, the ones formed by complex cells. The new species discovered are archaea that were called Thor, Odin and Heimdall, simpler organisms that however have some characteristics found only in eukaryotes and together with another archaea family called Loki whose discovery was announced in September 2015, form a group that was called the Asgard archaea.