Biological growth system resembling a tree or even certain types of coral. I've always wanted to do something like this since my tree generator.

You can click the movie to restart the system.

One interesting aspect of the growth sequence is that there is a limited number of branches operating at any point--if that number is exceeded via recursion, the new branch is saved and activated later once another branch stops growing. That is why you can notice that once the first set of branches is completed, more branches will begin to grow within the tree, filling out the shape.