Several "fundamental" shapes compete with Pyramids for the fundamental building block of Nature:
Ovoids are the "M&M" candy shape. Packaging Engineers have proven that such a shape is the optimal stacking shape for liquid containers, better than Spheres. I reject both however as there would be "space" between adjacent ones. Since "space" is exactly what we are trying to describe (and fathom), this is unacceptable.
A Cube like a Pyramid would not have that problem*. But a Cube, the second simplest platonic solid, is not as simple as a Pyramid. The Universe, many feel (e.g. Albert Einstein) is based on very simple principles. I feel so as well.
"Quantum Foam" as proposed by John Wheeler in 1955 may indeed be the way that Nature exists, but if so, QF should be composed of something, and this website suggests it's made of Pyramids/Tetrahedrons*.
I do not reject "Quantum Foam" nor do I embrace it. It has its points in describing what Experiments and Experimental Results reveal.
I just choose to dig a bit deeper.
* - Actually a Tetrahedron WOULD have the problem of NOT filling space, but there's an "out." I address the problem in the post "7. The Tessellation Problem." Test yourself and see if you can figure it out before going there.