Yea they are kinda confusing, especially when you get into the 3D ones like klien bottles and roman surfaces. I also recently learned that if you make a mobius shaped transmission line (like a ladder line) and you send a pulse down it, that pulse will continue looping until it dissipates (or forever if it is a superconductor).
https://www.microwavejournal.com/articles/21001-printed-reso...
I have no idea if there are any advantages over a simple planar circular loop though.