Complex sentence: Little is known about his past except that he comes from an incredibly long living species, as Larfleeze is said to be over several billion years old: he was taken from his parents for reasons yet to be revealed and forced to work as a slave.
Split into simpler sentences: Little is known about his past except that he comes from an incredibly long living species, as Larfleeze is said to be over several billion years old. He was taken from his parents for reasons yet to be revealed and forced to work as a slave.