Does it move or stand still? hmmmm

This optical illusion seems to never stops moving.This optical illusion looks like a moving picture but it is only a still image that tricks your eyes with a combination of size, shape and color that makes the optical illusion appear to wave back and forth. The image itself is very simple made of 2 shapes and 4 colors but the combination of the shapes and colors keeps your eyes from being able to focus well making it appear to be moving.