Wikipedia
BrainTwist
The Hoberman BrainTwist is a 3D mechanical puzzle designed and marketed by Chuck Hoberman's company Hoberman Designs. The puzzle is in the same family as the Rubik's Cube and other puzzles that involve manipulating and scrambling colored face elements with the goal of returning them to their original order from a randomized state, commonly called twisty puzzles. This puzzle is unique in that in addition to solving one set of tetrahedral faces the puzzle can be flipped inside-out through an intermediate stellated shape to reveal another (dual) tetrahedron with a set of 4 different colored faces. The puzzle also has an alternate solution in which the apices are each a uniform color.