Optical Illusions to Make Things More IInteresting :D

Are the lines straight or not straight. (It's suppose to be straight!) =]
When you look at it, does it move? It's suppose to move like a wave. Look closer if you really can't see it. It's a very good optical illusion. :D
Is this a polar bear trying to get out of the freezing pool in the ice or a seal crawling on the ice?
Can you figure out what's wrong with this box? It's playing tricks on your eyes. ^^