Nature engine (animation video)

My entry to Houdini challenge provided by Houdini по-русски youtube channel.
Analysis and evaluation of this work here (rus) - https://www.youtube.com/watch?v=5Stc9Q-2x_8
The goal of this challenge was to create content that represents perpetual motion machine and play this theme creatively.
The main condition - is to make work using Houdini only.