Bubble in my Hammer corals

[Doug 7727]

I don't know what's going on with my hammer Coral it was happy and now it has formed a bubble in the center of two of the branches I don't think that the pictures that I have do it justice but any help any advice I'm not dosing anything I'm just using resalt doing water changes regularly and it's I guess not happy and I don't know how to make it happy. Please help me with this as it is my favorite coral I have.

 

[Reefing Madness]

 

[Terry Mattson]

What ever happened to your Hammers and that bubble. I had one on my frogspawn. It went away after 2 months. And then one formed on another head. Otherwise they extend when lights come on.

 

[JT26]

It’s a good sign of splitting head. I have one right now and seem to be splitting into 3 heads. Look like a bubble cancer