I can highly recommend building your own falling sand simulator. It's really fun to see how such simple rules create emergent behaviors. Sand pixels tries to move down, then diagonally down. Water does the same, then tries sideways.
Me messing around with it eventually resulted in a game I'm now working on full time (think Noita meets Factorio): https://store.steampowered.com/app/2764460/Sandustry/
I still don't know what it is.
https://sandboxels.r74n.com/new-home
It doesn't explain why though, which is the most obvious question.
Sort of igneous, because it came out of a volcano, but sort of sedimentary, because it starts out as an accumulation of powder that becomes a solid piece.