Gömböc!

contributors at Atlas Obscura:

In 1995, world-famous Russian mathematician Vladimir Igorevich Arnold proposed that a class of convex, homogeneous bodies, which, when resting on a flat surface have only one stable and only one unstable point of equilibrium, must exist. (In unstable equilibrium, the body will fall out of equilibrium no matter how you push it). A few years later in 2006, his idea was proven by Hungarian scientists, Gábor Domokos and Péter Várkonyi, by constructing a physical example. Meet Gömböc.

Gömböc is basically one of the cutest superstars of mathematics. Its name comes from gömb, which means “sphere” in Hungarian.

more here.