Hi All,
Hope everyone is having Happy Holidays.
This illusion is just ultra cool: http://games.yahoo.com/blogs/plugged-in/dino-eyes-watching-creepy-illusion-212150695.html
At first you will think “there has to be a trick” but they reveal that it is your mind that is playing the trick. 
love it, must find a building plan …
edit:
find a horse
and the Dragon
http://www.grand-illusions.com/opticalillusions/three_dragons/
Its stuff like this that reminds us that our brains have a very humble beginning which isn’t that far away in some ways.
The creepy thing is, even that you know it, at the moment you don’t see the back side anymore, it snaps in again.
Yea. And no matter how hard I look at it I’m unable to see it with the face concave once the back is hidden.
I printed out one of the original Jerry Andrus dragons years ago, and I’ve had it sitting on my desk ever since.
A few things to note:
If you’re going to print this out, you’ll probably want a large-format printer. Doing it as a single sheet on 8.5x11 (or A4) will yield a pretty small dragon.
I printed it on card stock, because the neck-to-head piece is pretty flimsy. Even on card stock it’s kinda wobbly, so I ended up putting a brace behind the neck (a simple piece of card stock scored and folded into a triangle).
In person, your depth perception will prevent you from seeing the illusion, so it only works when you close or cover one eye. Cameras have no depth perception, so it always works on film.
That being said, I recommend it highly. It’s a very impressive illusion. My wife doesn’t like it, it creeps her out.
I just built a 15cm blue dragon.
It’s not only important to close one eye, it also works best in diffuse light.
If you have directional light, the brain calculates that in to get a correct 3D interpretation.
I like it!!