Anti-temporal matter
A powerful spark of anti-temporal matter, also called anti-time, existed inside the Taaron Ka diamond. The matter moved backwards in time, such that its earliest moment from an outside perspective was its destruction.
The truth of the anti-temporal matter's origins was unclear. The Curator suggested that when the Timeless Child was introduced into the universe, the universe had to compensate by adding a negative equivalent to the Child's power to balance itself out again. However, the Division believed that the matter originated as a spark from the Eye of Harmony.
The spark followed the First Doctor following the Doctor and Susan's escape from Gallifrey, and ended up in a temporal rift at the island of Brittia during the Doctor's first encounter with Earth. There, the Valeyard attempted to absorb it to gain power, but was stopped by the Division and several incarnations of the Doctor, who rewove the Valeyard's energy into a protective shell around the spark, creating the Taaron Ka.
The anti-temporal matter would be carried as a spark inside the diamond for the entirety of its history, backwards through time, until eventually the Valeyard's protective shell would wear out and the anti-temporal matter would explode, creating the Solar System. (GAME: An Unearthly Power [+]Loading...["An Unearthly Power (game)"])
