For me it is Cellular Automata, and more precisely the Game of Life.
Imagine a giant Excel spreadsheet where the cells are randomly chosen to be either “alive” or “dead”. Each cell then follows a handful of simple rules.
For example, if a cell is “alive” but has less than 2 “alive” neighbors it “dies” by under-population. If the cell is “alive” and has more than three “alive” neighbors it “dies” from over-population, etc.
Then you sit back and just watch things play out. It turns out that these basic rules at the individual level lead to incredibly complex behaviors at the community level when you zoom out.
It kinda, sorta, maybe resembles… life.
There is colonization, reproduction, evolution, and sometimes even space flight!
I can’t remember if it was a youtube video or a paper or an article or what, but I saw something explaining that, based on one interpretation of Einsteins equations, past the point of singularity, space and time invert. This would mean that the longer the black hole exists around in “our” universe (in absolute terms), the larger it becomes on the inside, and the larger it gets on the outside, the longer the inside universe would persist. I feel like you would have liked it, if only I could remember what it was. :(
The thing I saw postulated both that the universe would reuse the matter the black hole absorbed, and that there would be infinite branching universes since each would develop their own black holes, but then you have an issue with regards to running out of matter at some point. Though I guess that could be solved if you assume every black hole must converge at the end of their containing universe’s lifespan, and all matter would be reused in whatever blackhole absorbs the blackhole containing that parent universe? Oh hey, we’re back to fractals again!
Personally I’m a fan of the idea of black holes as topological stars that fall in line with string theory, but there have been so many hypothetical frameworks coming out in recent years that are just fascinating to think about.