Personal explorations done in Houdini.
These tests start with a simple shape like a pyramid or cube, convert them into signed-distance fields, and move the surface voxels through a system. The growth comes by moving them along the gradient (similar to normal) of the previous frame, resulting in an outward growth. That is then combined with other attributes like the curvature or laplacian flow of the surface, along with curl noise to create organic movement. In some explores, other attributes like color were advected with the surface rather than being added after the simulation.
The results are these wild organic forms which I love to see develop during the simulation. One of my favorite things in Houdini is that changing one variable or order of operations can result in a totally new and unexpected result.