Spinning Fun

Dec 2015 on Facebook I saw another post about optical illusions. (see circle illusion and wave illusion for more fun as well).
https://s-media-cache-ak0.pinimg.com/originals/3d/82/5b/3d825b28e636b65951760f412d5519b5.gif

This looked like a fun thing to try in Houdini, so I did: