Neovius surface

In differential geometry, the Neovius surface is a Triply periodic [minimal surface|triply periodic] minimal surface originally discovered by Finnish mathematician Edvard Rudolf Neovius.
The surface has genus 9, dividing space into two infinite non-equivalent labyrinths. Like many other triply periodic minimal surfaces it has been studied in relation to the microstructure of block copolymers, surfactant-water mixtures, and crystallography of soft materials.
It can be approximated with the level set surface
In Schoen's categorisation it is called the C surface, since it is the "complement" of the Schwarz P surface. It can be extended with further handles, converging towards the expanded regular octahedron