Via Europa Malynicz, “these”:http://www.psy.ritsumei.ac.jp/~akitaoka/rotsnakee.html are some of the most disturbing illusions I’ve seen. Be warned, the images in that link do have the capacity to produce at least mild dizziness, so don’t click the link if you are prone to dizziness. I should also add that not everyone seems to see the illusion, but I at least am extremely misled by it.