Not mentioned in the piece but these particular fractals have a name that nicely matches the content - IFS (Iterated Function System) fractals. A bit more here
https://en.wikipedia.org/wiki/Iterated_function_system
Note that the grey pixels can actually carry a state that their children can derive from. Some children may then turn black/white depending on their state. So in theory lambda screen can show any fractal, not only IFS.