This may be only tangentially photo-related but I think it's of general interest to anyone in the visual arts. I found the graphic below, the album art for Animal Collective's new album, over at Horses Think.
I swear this is not an animated gif. Even if the graphic is converted to hard copy or grayscale, the ovals still swim. I've seen some strange optical illusions but this one takes the cake.
As a bonus the art reminds me slightly of the cover to Fear of Music, an album which may not swim but features fantastic music.
Hold the paper up to the light. Some rays pass right through. Expose yourself out there for a minute. Some rays pass right through... If you feel yourself humming along, you were born at the right time.