Just some fun implementing a coral growth algorithm in Houdini roughly based on the following papers:
J. A. Kaandorp: Macroscopic Modelling of Environmental Influence on Growth and Form of Sponges and Corals Using the Accretive Growth Model
R. Merks, A. Hoekstra, J. Kaandorp, P. Sloot: Models of coral growth: spontaneous branching, compactification and the Laplacian growth assumption
The setup is quite simple and basically a bi-directional simulation model in which the environment (sunlight, fluid flow, nutrient concentration) influences the growth process but also gets influenced likewise by the growing structure itself. The images below are visualizing this interrelation by showing the resulting geometry after some of the environmental conditions have been changed.