Ceres

Ceres was a dwarf planet located in the asteroid belt between Mars and Jupiter. It was home to the Cerulians, who used cerulium to create a two-class system, the Masters and the Scribes. The Masters incorporated cerulium into bracelets and used them to control the Scribes, which they would use as slaves. Eventually a symbiotic relationship developed between the two; The Master was enchanted by the Scribes, who had no thought but to compliment and assist the Master. They were so amused with one another that they were oblivious to the threat of an incoming asteroid which destroyed their civilisation. Chunks of cerulium remained, some of which came to Earth in 2050 and were used by Inspector Drake in his plan to create a mindless population of obedient drones. However, K9 destroyed all the bracelets and foiled the plan. (K9TV: Sirens of Ceres)

Although Ceres was never referred to as being the same Ceres as the dwarf planet located between Mars and Jupiter, it most likely was, as its closer distance to Earth would make it more possible for the cerulium to arrive.