I once experienced the carpet morphing into a fractalized Aztec mandala, which I then fell into and spiraled downwards through into a vast lime colored underground sea in a cavern full of purple bats.
This happened while I was trying to have sex (amazingly, we succeeded, it helped that my wife was sober).
I have seen then on the brushed aluminum of my laptop at the time on regular (large dose) LSD… and I certainly see them (and strings connecting the present to the “future” on n,n-DMT.
Seriously, though... Is there some fractal geometry to the way our neurons are interconnected/communicating that's responsible for producing the kinds of visuals we see under the influence of certain substances? Or do we still have way too much to learn about the brain before we answer questions like that?
It's more that many fundamental laws of our reality are fractal-like and as we impair our critical thinking functions and neural circuits with psychedelic drugs, these underlying layers are revealed.
That's my theory, anyway. Based on nothing but vibes.
There was some 1990s documentary about fractals, narrated by Arthur C. Clarke (I think), where he said something along the lines of "I've not tried this myself, but I've been told there's certain illegal chemicals that can cause hallucinations that look like fractals".
(I have this on VHS tape somewhere. Should probably digitise it.)