Crystal Math XVII: Opinion of φ

[muon2]

I voted freedom number because it is the golden ratio, but it only links geometry and algebra. I couldn't go beyond that since it's not part of my favorite equation which binds the symbols of counting (1), geometry (π), arithmetic (0), algebra (i), and calculus (e).

e^iπ + 1 = 0

[muon2]

I prefer the rhombic dodecahedron. It is one of the few solids that can tessellate space and appears naturally in crystals such as garnet and in the bonding structure of diamond. You did say this is Crystal Math.