Did You Know? #49

What does a Penrose Triangle have in common with a Blivet?

Both are impossible objects. An impossible object is a type of optical illusion consisting of a two-dimensional figure which is interpreted as representing a projection of a three-dimensional object although it is not geometrically possible for such an object to exist.

The top image is a Penrose Triangle and the bottom image is a Blivet (also know as a devil's fork).