A tenth of the grains carry most of the load, along a sparse network of nearly-straight chains, while the rest carry almost nothing — photoelastic fringes and all; tap it and the network rearranges onto a completely different set of grains with no visible change to the packing.
Drawn with: a WebGL2 shader.
Reacts to and looks like: gpu, webgl2 and audio-reactive.
Family: Visualiser.
Runs in your browser. The preview above is the same program the renderer uses.