Feature

Swirling Seas, Crystal Balls

Spirals of triangles crinkle into intricate structures

A field of triangles crumples and twists into a wavy crystalline sea. A crystal ball sprouts spiraling, labyrinthine passages. Faceted bricks stack snugly into a tidy, compact structure. Underlying each of these objects is a remarkable geometric shape made up of a sequence of triangles—a spiral polygon that resembles a seahorse's tail.

An S-shaped sequence of ever-smaller triangles, the spidron underlies a host of novel structures, such as the starlike three-dimensional form shown here. ~~ M. Pelletier, D. Erdély, and W. van Ballegooijen

TWO ARMS, TWO ARMS. The spiral arms of a spidron consist of alternating sequences of equilateral and isosceles triangles. ~~ Erdély