Each cube can be positioned a pair of tetrahedrons And if you have a good memory, you will remember and pentagondode-kaedr, also belongs to this class of symmetry. The picture clearly shows how the tetrahedron can be formed from the cube. The rest of the Platonic solids also belong to the cubic system. The ancient Greeks, we think, would be terribly upset if they knew that such a mundane mineral as pyrite, has the same symmetry as their "perfect" body. Colorful world Kaleidoscope I do not know, dear reader, have you had a child kaleidoscope, but if not, then something is irretrievably gone past you ... Kaleidoscope - a tube looking in you can see a fantastically beautiful pattern of colored polygons. It is necessary to turn the toy inside hear a slight rustle, and will create a new ornament. And so with every turn, and every time a new pattern - one another unexpected and beautiful.