Ancient Essence

Ancient Essence is currency that is used to upgrade items at the Cosmic Crucible.

Even in the early game will can randomly find small amounts of it: it sometimes drops from monsters, etc. Some artifacts can be exchanged for Ancient Essence at the shops of Science Outpost.

In the late game, there are two plentiful sources of Ancient Esssence: Soulleaf Seed will allow you to cultivate it in greater quantities, while the Precursor computers (such as the Precursor Mainframe) will yield a small amount of Ancient Essence in addition to their normal Research yields.