A seashell like a Moebius strip
The border of a Moebius strip consists of only one circumpherence: this animation shows what happens to the Moebius strip if we move this circumpherence in order to position it in the three-dimensional space in the usual way. The most natural way to do that produces as a result the so-called "crossed hood": instead, this animation leads to a seashell surface and during the process the Moebius strip never shows any self-intersection. Some buttons give you the possibility of cutting the Moebius strip (as we can see in the figure) and seeing it transparent, in order to visualize its structure.
animazione di Gian Marco Todesco