Paradoxical Arrow of Kokichi Sugihara

The Japanese mathematican Kokichi Sugihara has developed this 3D Arrow model:

You can can get some idea of what's going on here when he picks it up and shows it from above:

ScienceAlert Article on Kokichi Sugihara:

This 3D Optical Illusion Will Make You Question The Shape of Reality  

More 3D Illusions by Kokichi Sugihara:

ScienceAlert: Ambiguous Cylinder Illusion

Many other fascinating illusions can be viewed at the...

Best Illusions of the Year Website 

Creative Sam's Video of the 7 Best Optical Illusions of All Time...

Including the Train Illusion which is somewhat like the dancer that spins two ways...