This is another great example of emergence. Complex behavior results from many individual particles following simple rules.
Here is another particle based life model
I learned about Clusters when Code Parade posted the following video explaining his version of Clusters he calls Particle Life.
The source code to Particle Life was generously shared here so I had a go at converting the code and playing with these myself.
Here are some of my results.
Extension Into 3D
Once I had the 2D version working, extending into 3D was the next step. These movie parts use the same settings as in the 2D movie above.
Both the 2D and 3D Particle Life are now included with Visions of Chaos.