Gomboc: World's First Self-Righting Object
Remember the 70's toy Weeble ("Weebles wobble but they don't fall down")? Well, no matter what position you place weebles in, they always sproing upright. They do this because their bottom end are weighted.But...
https://www.neatorama.com/2008/01/27/gomboc-worlds-first-self-righting-object/

