He and Primus clash many times, the force of their battles wiping out the very life Primus had been created to protect. To stop the destruction, Primus shifts the battle to the astral plane. In shifting the battle back to the physical universe without time to properly generate their energy forms, Primus entraps both himself and Unicron in two barren asteroids. Over the eons, Unicron learns to psionically shape his asteroid, and transforms it into a metallic planet, and then into a gargantuan robot. Primus, fearing that the following suit by forming himself in a similar manner will simply pick up the conflict where it had left off, seeks an alternative way to defend the universe against the threat of Unicron by turning his asteroid into Cybertron. He populates it with robotic beings that, like Unicron, can alter their forms, giving rise to the transformers.