Diamond [v4]
1: Click / tap the power button to start the visualizer and click / tap anywhere to stop it.
2: Stare at the center of the visualizer without blinking for 20 seconds.
3: Start at something else.
This is a motion aftereffect.
Staring at the visualizer longer will lengthen the effect. You can manipulate the layout with your browser's zoom controls.
Use at your own risk, I have no idea how this may affect your vision.