Diamond
1 Choose something to look at.
2 Push start and stare at the center of your screen without blinking for 15 seconds.
3 Then look back at that something.
START
Click / tap anywhere to stop
This is a motion aftereffect.
* Staring longer will lengthen the effect.
* Screen size, and zooming in or out will change the visualizer.
Use at your own risk — I have no idea how this may effect your vision.