The Gömböc, a mono-monostatic object that is able to right itself no matter how you place it. It does not work like a weebl— its weight is evenly distributed. It is the mathematically-determined precise shape that allows it to always end up in its upright position.
If its main job is to remain rightside up, this thing is the ultimate in form following from function.
(uncredited photo via Wired)