Now don’t say we didn’t warn you, but this optical illusion is seriously weird.
The rotating crosses seem to be changing the shade of the background in the image below. Stare at it long enough and you’ll probably go crazy.
First the white crosses rotate one way and then the black ones the other, creating the weird illusion. This is an example of figure-ground organization, where your brain tries to decide what is the focus and what is the background.
Plus, you know, it’s just kinda trippy and weird to look at. Enjoy.