The Anti-Backwards Crystal is one of two crystals accidentally created by Farnsworth. When Farnsworth misplaced the crystal, it became the "D12" dice for Cubert, Dwight, and their friends playing Dungeons & Dragons. Mom's sons, (Walt, Larry and Igner), attempted to steal the crystal to avoid it and the other crystal joining, which would make dark matter unusable as fuel. Farnsworth eats it and hugs his son Igner, who had eaten the other crystal. The Anti-Backwards Crystal explodes, making all dark matter worthless.