True-vacuum bubbles nucleating in a false vacuum that inflates faster than their walls can cross it, so they are stranded from each other forever — eternal inflation, with the saturating comoving radius that is the whole reason the bubbles never fill the space; each hit nucleates one.
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.