I have a Hammer that had brown jelly once. Killed the lower branch. But now it has reproduced and the made two more branches. Good Luck w/ finding wuts wrong w/ it. I see that your bottom branch has no polyps on it. Thats wut mine kinda looked like after its attack.
Well after doing all sorts of checks I think I figured out the problem. My sg was up to 1.0275 and my water temp had been running around 82 to 83 from the hot weather we had in my area over the last couple days. The sg went up because of me not being able to read and I added to much salt to my water. tomorrow I will be picking up a 10 gallon to use for frags so i'll put them in there.