Antimatter is the quantum reverse of ordinary matter. Contact between antimatter and ordinary matter results in mutual annihilation, all the mass being converted into energy. In the Star Control universe, antimatter is used as both a fuel and a weapon. It is also classified as an Exotic and can be collected on the surfaces of unique planets.
At least some, if not all, Hierarchy vessels also rely on a stabilized antimatter fuel. Commander Hayes explains that this is the reason the Earth Starbase is capable of synthesizing and refining this type of fuel. Fortunately The Captain's Precursor Flagship uses this same type of fuel in its Antimatter Thrusters.
The Umgah Drone principal weapon produces a wide cone of antimatter. The Zoq-Fot-Pik Stinger vessels also employs antimatter, a spray of tiny antiparticles, as a weapon. The ultimate antimatter weapon is the Utwig Bomb, a Precursor planeteering tool.