I was at the G4G (maths, puzzles, gadgets etc) conference this week. This was one of the “exchange gifts”. I don’t know the creator, if someone knows, please let me know.
It is a torus tiled by 5 squares. I was surprised this is possible, so I figured out a fundamental polygon. This also turns out to be a square, which is possible because ( 5 = 2^2 + 1^2) .
