Wurst-Katastrophe (german for "sausage catastrophe")
Spoiler:
When you try to find the configuration of the least-surface area packaging for n spheres it starts out as a 1-dimensional tube (Wurst) for low n (which is why tennis balls are wrapped that way). At n=55 this suddenly jumps to a three dimensional cluster (Wurst-Katastrophe). There exists no n for which a 2 dimensional configuration is best