The Primagen (also known as Prima Materia) is a substance created and harvested by the Progenitors in the Garden-World inside the World Farm used as fuel. To the Progenitors, Primagen is easily farmed and widely used. The Primagen was additionally employed as a catalyst to evolve the Kree from their primitive form. The Kree's failed attempts at re-creating it resulted in the much less pure Terrigen; Antigen and Amphogen. To the Kree, the Primagen became a forbidden legend, of which only high-ranking Kree soldiers have the clearance to discuss it.
A millenia afterwards, a group of Inhumans learned of the existence of Primagen through the Plex Intelligence while looking for an alternative to Terrigen, all of which had been destroyed by Medusa. They eventually reached the World Farm, and barely made it alive to a Primagen deposit. They managed to escape with samples of Primagen and returned to Earth.
- Maximus compared the difference between Terrigen and Primagen to the quality between fish guts and caviar.