The perptual diamond: The diamond remains fixed in one place but appears to move up, down, left, or, right. See how far away you can be from your screen before the effect goes away. From https://t.co/XRFKTtjOfm pic.twitter.com/af7BOUCvfC— Arthur Shapiro (@agshapiro2) June 2, 2019
This optical illusion is a wily one.
You know that the diamond is fixed in place, but your brain keeps telling you that it's moving.
Here's an interactive demo over at Shapiro's website that you can play with.