What can you see in this optical illusion? Eight points spinning around?
No, the points are moving on a straight line back and forth.

You don't believe it, than click the app.

With one point, you can see, it is moving from left to right and back.

With two points, it is also no problem to see the lines.

But with four points, it is more difficult to follow the lines with our eyes. The brain will see the circle moving.

And if all eight points are moving, you must focus just one point to see the linear moving.

Have fun with it
and show it to your friends