Triceratium, a triangular diatom

Diatoms are single-celled, plant-like organisms found throughout the world’s oceans and freshwater. They form dense, short-lived blooms that the rest of the ocean food web depends on, like microscopic rainforests that come and go with the weather.

Their exoskeletons are made of silicate (glass) and can take a huge variety of geometric forms. Triceratium diatoms are often triangular, although they can take other shapes as nutrient conditions change.

Like all diatoms, their exoskeletons are made of two halves that fit together like the lid and base of a traditional origami box (masu). Dasa Severova played with this fact to design a Triceratium model that you can keep your collection of beach pebbles in. You can download complete folding instructions here (16 MB PDF).

The model starts from an equilateral triangle: the last page of the instructions shows you how to construct one from a rectangle or square.