The Soma cube is a solid dissection puzzle invented by Piet Hein in 1936 during a lecture on quantum mechanics conducted by Werner Heisenberg. Seven pieces made out of unit cubes must be assembled into a 3x3x3 cube. The pieces can also be used to make a variety of other interesting 3D shapes and are given with the instructions. There are 240 distinct solutions of the Soma-cube puzzle. Dimensions: 2 3/4" x 2 3/4" x 2 3/4"