At the door of Plato’s Academy, around 340 B.C., this phrase is engraved: “Let no one ignorant of geometry enter.”
The support structure is an endless tube forming a cube, a design and construction challenge in its own right. . The five Platonic Solids hanging in the form of a mobile are the icosahedron (20 triangles,) the dodecahedron (12 pentagons), the tetrahedron (4 triangles), the octahedron (8 triangles), and the perhaps the most common, the cube (6 squares). These are the only three-dimensional shapes that can be created from identical two-dimensional shapes.