The Proterozoic Eon, which lasted from 2.5 billion to 541 million years ago, is the most recent part of the Precambrian supereon. The Archean Eon follows it and precedes the Phanerozoic Eon. This era is characterized by significant geological and biological changes, including the formation of stable continents, the rise of oxygen in the atmosphere, and the emergence of early life forms.
The Proterozoic Eon (2.5 billion to 541 million years ago) saw the rise of the first animals, known as metazoans, after the evolution of eukaryotes. These early animals were primarily soft-bodied and marine-dwelling, with the Ediacaran biota being a key example of this fauna. While some resembled modern jellyfish and worms, others were unlike anything seen before or since.