 Mathematicians Gábor Domokos of the Budapest University of Technology and Economics and Péter Várkonyi of Princeton University designed a homogeneous object called a "gömböc" that has exactly one unstable balance point and exactly one stable balance point.Just as a bottom-weighted (nonhomogeneous weight distribution) sphere would always return to the same upright position, they found it was possible to construct a shape that behaves the same way.After that, they noted the similarity to the Indian star tortoise and subsequently tested 30 turtles by turning them upside down.