Terullian was a material not generally found in the Mutter's Spiral. (TV: The Sontaran Experiment) It could be found in the Antares system. (PROSE: Lords of the Storm) It had a wide variety of uses. The Sontarans used terullian in their drive system for robots, one of which was used by the Sontaran Styre of the G3 Military Assessment Survey. They also used it in a diode bypass transformer, which was used by Sontarans to feed on energy to recharge. (TV: The Sontaran Experiment)