Seed of Life

The First Ancestral Race were ancient progenitor aliens which attempted to seed life on planets throughout the galaxy. "Seeds of Life" were created in two varieties: Adam-like creatures which were where transported to their destinations in vessels termed "White Moons" and creatures like Lilith, which were transported in "Black Moons". Planets which received a White Moon became dominated by Angel-like life-forms, while planets which received Black Moons became dominated by human-like life-forms.

Adam landed on Earth billions of years in the past, and her "White Moon" became embedded underneath the land mass that would become Antarctica. However, some time later the Black Moon containing Lilith crash-landed violently into Earth, in the event termed First Impact which created Earth's Moon. A Black Moon and a White Moon were never meant to land on the same world, resulting in Adam and Lilith's progeny coming into direct conflict.

Lilith spread the primordial ooze from which "normal" terrestrial life on Earth evolved over the course of billions of years, while Adam remained inactive until he was forcibly awoken by the Katsuragi Expedition, resulting in Second Impact.