It's true - they're a ... oh, what's that beautiful shape
   called... well, they're
   [1]https://en.wikipedia.org/wiki/Borromean_rings - but it shows
   up in a lot of places.* It might be a trinity knot?* all I can
   remember is the rings.* Oh!* See:
   [2]https://en.wikipedia.org/wiki/Efimov_state for the graphic on
   the Halo Effect - I made that - it's a good example of 'three'
   building on each other for exponential growth.

References

   Visible links
   1. https://en.wikipedia.org/wiki/Borromean_rings
   2. https://en.wikipedia.org/wiki/Efimov_state