Triply periodic surfaces

Schwarz P-Surface

Triply periodic minimal surfaces are invariant under three independent translations. One best visualizes them in terms of a fundamental piece copies of which are stacked together to produce the whole thing.
Schwarz P-surface to the right and left.

4 copies of P-surcface

At the end of the 19th century, H.A. Schwarz and his students found a few examples, and later so many more were discovered that we don't even have a satisfactory description of what is known to exist.
Neovius' surface to the left and Schwarz' H-surface to the right.

Schwarz H-surface