Bad Branch on Frogspawn

Here is one branch head of my frogspawn that is only half-filled with tentacles. What happened? Why did it do that? What is it?

If I frag the branch off will it grow back correctly?

Here are some pics:

 

If it's not getting enough light (which is what the case looks like by the pic) then fragging it and moving it to better light would definately be an improvement. Sometimes, once you get new heads that grow underneath the larger, more established heads, they get deprived of light.

This will also help it heal too.

 

is that a recently grown new branch?

 

No the branch is not new because it is about an 1-1.5 inches in diameter. This is just the first time I noticed it since it is usually covered up by other tentacles. It is towards the top of the coral so it gets enough light (bad photo I guess). Here is a pic of the whole coral and the placement in the tank.

 

Wow! That's huge!! I would suspect fragging it and getting the smaller pieces out in more light will be good. Nice tank by the way!!

 

Will it grow another head if I frag it or is it a goner? If so I'll just keep the bad head