Baguenaudier
Baguenaudier (pronounced [baɡnodje]; French for "time-waster"), also known as the Chinese rings, Cardan's suspension, Cardano's rings, Devil's needle or five pillars puzzle, is a disentanglement puzzle featuring a loop which must be disentangled from a sequence of rings on interlinked pillars. The loop can be either string or a rigid structure.
It is thought to have been invented originally in China. The origins are obscure. The American ethnographer Stewart Culin related a tradition attributing the puzzle's invention to the 2nd/3rd century Chinese general Zhuge Liang. It was used by French peasants as a locking mechanism.
Variations of this include the Devil's staircase, Devil's Halo and the impossible staircase. Another similar puzzle is the Giant's causeway which uses a separate pillar with an embedded ring.