Tetrahedron: Four equal-sided triangles each sharing a vertex with two other identical triangles.
A simple tetrahedron always encloses four half-sized tetrahedrons and an octahedron. This particular model on the left was used on television to demonstrate the close working relation between people, products, and processes in order to create a profitable business.
These three tetrahedrons form a base for an octahedron as seen here which have been dubbed “tetrahedral-octahedral couplets.”
The ever-so-important five tetrahedral configuration, called a pentastar within this website, opens discussions about quantum geometries, quantum fluctuations, and imperfectly fitting combinations.
That is an octahedron within it with the red, black, and blue tape. A fourth color, white can not be easily discerned within this image.
The next image on the right is an icosahedron, a twenty tetrahedral cluster, that imperfectly coheres.
Please note: This article was begun on May 3, 2018. It is still a rough draft. It has its origins at MIT in 1979.