Solids of Constant Width (Reuleaux Shapes)

Spheres are not the only solids that have the same width at any incident angle. These shapes have the same width (height) no matter how they are rotated or rolled.

Both Reuleaux tetrahedrons and revolved Reuleaux triangles present the same properties. The only difference is that the center of mass of these shapes does not remain at the same height when rolling around which leads to a unique and interesting type of motion.