The Anti-Backwards Crystal is one of two crystals accidentally created by Hubert J. Farnsworth. When Hubert misplaced the crystal under the walrus tank, it became the "D12" die for Cubert J. Farnsworth, Dwight Conrad, 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. Hubert eats it and hugs his son Igner, who had eaten the other crystal. The Anti-Backwards Crystal explodes, making all dark matter worthless.
- The Anti-Backwards Crystal is a geometric solid known as a regular Dodecahedron (twelve faces, twenty vertices, thirty edges). The other crystal is a regular Icosahedron (twenty faces, twelve vertices, thirty edges). The Dodecahedron and Icosahedron are mathematical duals; each face of one corresponds to a vertex of the other.