Bubble on Mouth of Hammer Coral has EXPLODED!

[fishfanatic06]

The mouth of one of the heads of my hammer coral had a large inflated bubble on it. Today it popped. Now there is this big, white mucus looking thing that is hanging out of where it popped.
Why did this happen?

 

[fish02]

Is it a branching hammer?

If so it's probably going to split really soon. Mine did the same bubble thing, and now my single head of hammer coral is turning into 10 or more. The bubble popped every once in a while because of fish hitting it, and my clown didn't help either.

 

[Bebo77]

zit?

 

[kookerson]

Mine just did the same thing last night, I wasnt really worried too much about it because he still looks really healthy today, but its nice to have an answer. : )