You can find a sculpture based on this figure on some Calculus (S) text book covers... Here is a a Maple worksheet that will show you how these images were generated. You can download this file to play with the figure yourself - but you must load it into Maple before it will be meaningful, however. In addition, below I have added another graphic of the one from the cover. And here are lots more pictures of this sculpture, and other similar ones.
Animation produced using
(And the idea of using the umbilic torus NC is "borrowed" from the HMCO home page.)