It looks like a cheesy consistency huh?
The symptom your leather is showing, is caused by a number of vairables(poor tank conditions, heavy sedimentation, toxins and improper lighting)
What you need to do are(actually two choices):
1) Cut off the infected area with a razorblade, making sure to cut into the healthy are alittle bit to make sure you removed all of the dead area, prohibiting the spread of the dead tissue.
2)Place 10 drops of Lugol's solution in one quart of water and soak the Sarcophyton(leather) in it for 5-10 minutes or so. That should help to restore and heal the infected area of the coral.
hope this helps!!!!!!!!!!!!! _________ 125gal.w/Mag9.5 return(dual megaflow)>Mag7 pump Aqua Cev180skimmer.Wave2k Hamilton Reefstar(2)250watthqi(mh)pend.a Yellow, Naso Tang Red Lip Blenny Percula Clown Demoiselles Niger Trigger F. Wrasses Ceriantharia Orn.Shrimp and Stars Hermits Queen Conch asst. snails> Stars Zoos shrooms Montipora Brains Gorgonians Favia Turbinaria(large+small polyp) Acropora Xenia Tridacna (CroceaMaximaSquamosa) Leathers <35+75gal.reef tank as well> 
"IF THE PHONE DOESN'T RING...IT'S ME"  jb  |