I enjoy the look of large brain/maze corals and I recently got this pink and green platy. Will it grow large and round just by building a skeleton under it or should it be placed on a larger rock? Also what is the typical growth rate of a health platy?
If you put it on a rock it will slowly encrust onto it. On the sand it will grow, just not as quickly. Stability improves growth rate ime.
in the wild it should start out by settling onto a hardscape and growing on top of that. Sea urchin can erode these brain coral , or they grow so massive that they end up sitting on the soft sediment. Large or small, they can exist on the soft sediment but if they are not anchored they can roll around in large storm currents, tsunami waves, etc. They end upside down or on their side and with time the coral will grow towards the light, or die if they get to beat up tumbling around.
HTH