This shape is known by various names ;Boys Surface,Semi-circular Canals,but I like "The Plane at Infinity".
This title is a quote from one of my favorite books called "Sensitive Chaos"by Theodor Schwenk about making sense of flowing forms in air and water.
I found 6 heavy industrial pipe elbows at the scrap yard and this is what I've made from them.I'm happy with the blending of the anticlastic pieces I made on the press to sculpt the mating of the tubes at the front and rear intersections.