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