The Recycling Symbol
In 1969 a competition was created to find a symbol to represent recycling. It was won by a 23 year old designer named Gary Anderson with this design:
Notice that the three half twists are not all in the same direction, with the two on the left and at the top folding upwards with the one in the bottom right folding downwards. This was no accident and it essentially makes two of the twists cancel out which makes the overall shape a Mobius Strip.
This is appropriate because the Mobius Strip, along with the Ouroborus (infinity symbol which comes from a snake eating its own tail) has connotations of forever and renewal.
However, the symbol is not copyrighted and like all public domain symbols it has many different forms. The most common today looks like this (spot the difference):
This one has all three folds in the same direction which makes this variation on a Mobius Strip have three half twists rather than one. In mathematics this 3-Mobius is less common although I do appreciate the additional rotational symmetry. Manufacturers are deeply inconsistent with which variation they use and while the later is more common, I have got into the habit of always checking and giving a mental congratulations to the product designers who have stuck with the original. I encourage you to join me in this behaviour, it is satisfying.
To end I thought I would show you my favourite recycling symbol from around the world. This one is from Taiwan and it creates a second set of arrows out of the negative space in the middle.