How does my coral grow? (LPS)

[Sean]

Hey Guys!

I'm not really a science expert, but can anyone explain in simple terms on how my Bubble, Tourch and Hammer coral grow? It's boggling my mind because to me they have such a hard shell on them that I just don't see how they could expand with all those soft tenticles on the inside. I would imagine they would create the shell on the inside and push it out.. but I could be dead wrong.