This document discusses different types of polyhedrons and round bodies. It lists tetrahedrons, icosahedrons, octahedrons, dodecahedrons, and cubes as examples of polyhedrons. It also mentions triangular, quadrangular, pentagonal, and hexagonal shapes. Additionally, it provides examples of round bodies such as cylinders, cones, and spheres. Finally, it notes relationships between shapes like a tetrahedron being self-dual or cubes and octahedrons being dual to each other.