Bonus points: I am remembering a video, perhaps it was Matt Parker or Veritasium, about the patterns that matrices formed from spheres can create. There was a demonstration with a toy made from ball bearings in a single layer beneath plexiglass that they tilted back and forth and discussed the ways the bearings arrange themselves. I can’t find it and I can’t remember the name of the theory or phenomenon that this demonstrates.

I bet someone here knows what I am talking about though.