There are some pretty interesting facts in the writings such as the reason growth tips can exhibit brighter colors and that brighter colored corals may have a slower growth due to the energy needed for the added light protection. Here is a quote...
We found the pink and purple proteins act as sunscreens for the corals by removing substantial light components that might otherwise become harmful to the algae hosted in their tissue. Corals rely on these light-dependent miniature plants, the so-called zooxanthellae, since they provide a substantial amount of food.