The names Egg of Columbus and Columbus Egg have been used for several mechanical toys and puzzles inspired on the legend of Columbus balancing an egg on its end to drive a point. Typically, these puzzles are egg-shaped objects with internal mechanisms that make the egg stand up, once the users discovers the secret.
Mechanisms typically used in such toys include moving weights, mercury flowing in sealed tubes or compartments, and steel balls rolling on grooves and pits.
The German company Pussycat sells a Columbus Egg that can be balanced by holding it upright for 25 seconds, then quickly inverting it. The egg will then stand on its pointed end for 15 seconds, then topple on its side.