These are fun things to code because they can surprise you. Even when you understand the rules, it can be delightful to see what grows.
https://www.reddit.com/r/creativecoding/comments/ezcaie/proc...
Someone coded procedural swimming with simulated tentacles. The post itself is a video and then they tell a little bit about it in the comments section also.
[Edit] found it http://levitated.net/daily/index.html http://levitated.net/daily/levWalkingThings.html
[1] https://www.researchgate.net/publication/258238188_Inventing...
If the book is inspiring it might be worth going through some of the insightful comments in that post.