The geological eon from 544 million years ago in which early forms of life were formed is the Phanerozoic Eon.

While life existed before this time, the Phanerozoic Eon is marked by the Cambrian Explosion, a period of rapid diversification and evolution of life, leading to the development of most major animal phyla.

However, it's important to note that life originated much earlier, in the Precambrian Eon, specifically during the Archean Eon (around 4 billion years ago). The Phanerozoic Eon simply marks a significant acceleration and expansion of life forms.