My thesis work was about creating synthetic texture using reaction-diffusion. Reaction-diffusion is a process in which two or more chemicals diffuse over a surface and react with one another to produce stable patterns. Reaction-diffusion can produce a variety of spot and stripe patterns, much like those found on many animals. Developmental biologists think that some of the patterns found in nature may be the result of reaction-diffusion processes. We can texture a computer model by simulating a reaction-diffusion process on the surface of the model.
Some squirrels have similar patterns.
Simulating reaction-diffusion textures on surfaces. I have made available two simple reaction-diffusion programs for people who wish to experiment with the process. You can download the source in this tar file . The Xmorphia site has an excellent illustration of the parameter space of a particular reaction-diffusion process. The animations here are wonderful.