Austin game developer Frank Force has won the Neural Correlate Society’s 2019 Best Illusion of the Year Contest with this “dual axis illusion”:

“This spinning shape appears to defy logic by rotating around both the horizontal and vertical axis at the same time! To make things even more confusing, the direction of rotation is also ambiguous. Some visual cues in the video will help viewers change their perception.”

The top 10 finalists are here.

12/18/2019 UPDATE: Good heavens, people are making these things. Five years ago Bill Gosper created the Lissajoke ambiguous roller, which rolls in a perplexing way:

And reader Joe Kisenwether has rendered Force’s illusion in reality — here the shape on the left spins about a horizontal axis while the one on the right spins about the vertical one:

The same thing rendered more slowly:

(Thanks, Joe.)