This 12-piece Altekruse Puzzle forms the asymmetrical shape of an abstract cube - the unique design is truly admirable compared to puzzles of the same caliber. Altekruse means “old cross” in German, and this puzzle was originally designed in 1890 by William Altekruse. Ever since its creation, the Altekruse Puzzle has been proving its worth as a staggeringly popular brain teaser. The puzzle’s construction is a level-two burr, meaning that two separate steps are required to release the first piece (unlike the regular solid burr types that have one move to unlock the key piece). Use this puzzle as a desk toy when you need to replenish the vigor of your mind, and an entertaining piece for the coffee table to challenge friends and family.