A Processing.py port of an old Nodebox sketch (by Lieven Menschaert ). It’s a great exercise for messing around with procedural generation. You can make these microbial beasties as simple or complex as you wish.
Before Processing.py, there was Nodebox 1. It’s was a neat, vector-based Python alternative to Processing. Since then, development on it has largely ceased – but now we have a Python mode in Processing 
The Nodebox 1 website still hosts a gallery of works; every now and then I port one to Processing.