The Cerulians were a species native to the planet Ceres. The Cerulians 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. (TV: Sirens of Ceres)