Pyraminx

Pyraminx was designed in 1970 by the German puzzle designer Uwe Mèffert.

It is a tetrahedron puzzle that can be twisted along any of the cuts. The object is to scramble all the colours, and then return them to their starting position again. 

Initially the puzzle was just for his own amusement, but after the success of the Rubik Cube, he realised there could be a market for it, and so he took the design to Tomy Toys of Japan in 1981. It sold more than 10 million pieces in the first year, and has sold many millions since then.