Once i have seen a 3d visualization of a surface with the following characteristics:
- it had three circular borders. If you imagine the surface inscribed in the earth globe, one of the borders would be the equator, and the other two would be, say, the latitudes of the polar circles;
- if I remember well, it was a minimal surface;
- if an ant came walking from the north pole, inside the "cone" formed by the surface, it would end up between equator and south polar circle of the south hemisphere, and vice-versa;
- if one looks vertically through said "cone", he sees a "pant", that is, he sees a bifurcation looking like two legs of the pant (i am not sure about it, but this is how I remember).
My failing memory suggested the name of this surface would sound similar to cathenary or cathenoid, but I have already discovered that these are other things.
Do you mean Costa's minimal surface?