Acans growth

[Kial]

My acans seem to be doing pretty well, I'm just wondering if they spread onto the rocks which they are sitting on?
I bought them on a small piece of rock

 

[nautical_nathaniel]

As they grow, they will form new polyps on the side and build their skeleton down and out, eventually they will smooth out to the point where you won't be able to notice the original frag area, but that could take a few years.