Introduced with the Transmetal 2 toyline in 1999, spark crystals are plastic bubbles in various colors, covering a vacuum-metal insignia of the allegiance of whatever Transformer possesses it (Maximal for Cheetor, Predacon for Dinobot II, etc.) They have been used on Transformers toys in several franchises since. In Beast Wars Neo, spark crystals seem to serve no other purpose other than to identify Maximals from Predacons, much like the rubsigns of old. In the Robots in Disguise line, spark crystals were only added to the Predacon sub-group. In the show, it fired a sort of laser blast.