Split Torus
This is a model of a sculpture by Karel Vreeburg.
The mathematical physicist John Baez paid some attention to the sculture and
the European Mathematical Society has used it on a cover for a scientific journal.
The torus is split by a triple twisted mobius band (3 times 180 degrees).
The resulting object is a trefoil knot.
N.J. Wildberger talks about Torus knots in his lecture
AlgTop26: Covering spaces(Starting from minute 37)
If you are curious about what topology is:
See the total beginners course in Algebraic Topology.