@wonderofscience@mastodon.social Here's a good way to see what's going on: right-click on the animation and save it as a video. Then, open it on mpv (or any movie player that allows you to change the frame rate). On mpv, hit `f` and then `[` a few times. The illusion is based on the shading of the edges. The thick lines joining the vertices just flash, but the _edges_ of those lines are also shaded, and that shade is what induces the motion. It's easier to see it than to explain it.