There are actually dolphins in that jar. I count 11.
Overhang or floor?
Pretty young maiden or gnarly old hag?
Man playing sax, or pretty face?
What's strange about this? Square 'A' and square 'B' are actually the same color.
These drawings are actually on sidewalks. Therefore, they are really flat surfaces.
Here is a link to some cross-your-eyes 3D pictures.
These images are NOT safe for work. But if you can cross your eyes good, they are some cool pictures.