https://en.wikipedia.org/wiki/Archaea
https://zh.wikipedia.org/zh-tw/%E5%8F%A4%E8%8F%8C
At some point before 2 billion years ago, small colonies of bacteria began to adopt the habit of living inside a common membrane.15 It began when a
small bacterial cell, called an archaeon,16 found itself dependent on some of the cells around it for vital nutrients. This tiny cell extended tendrils towards its neighbours so they could swap genes and materials more easily. The participants in what had been a freewheeling commune of cells became more and more interdependent.
Eukaryotes emerged, quietly and modestly, between around 1,850 and 850 million years ago. They started to diversify around 1,200 million years ago, into forms recognizable as early single-celled relatives of algae and fungi, and unicellular protists, or what we used to call ‘protozoa’. For the first time, they ventured away from the sea and colonized freshwater ponds and streams inland. Crusts of algae, fungi and lichens25 began to adorn seashores once bare of life.
Some even experimented with multicellular life, such as the 1,200- million-year-old seaweed Bangiomorpha,26 and the approximately 900-million-year-old fungus Ourasphaira. But there were stranger things. The earliest known signs of multicellular life are 2,100 million years old.
