Board Thread:Questions and Answers/@comment-4503935-20131202034149/@comment-14086575-20141009132809

The answer may be found on the episode "Arrested Development"; in a scene where the kids were playing dodgeball, a young girl choose Ben, to be in her team, over Billy's. It's very likely that Billy used that girl's likeness, to build Mazuma, while trapped in Dimension 12.