I have taken the bubble out by getting at them at their base, and gently and carefully picking them off of the rock with a needle.
You have to be VERY carefull not to pop them, so be sure to have the needle between the rock and the base of the bubble. Even better if you can take the rock out of the water!!!! Then rinse the rock in a bucket with new or old tank water.
Get it before it spreadssssssssss......
Always check frags you get from others for them before placing them into your DT. I didn't, and later found the darn things.
if you dont have any other living creatures in or on the rock, I'll probably just take the rock out and leave in f/w for a awhile AWIBrandy was right, what ever you do, DO NOT POP them, a lot more problems will occur if you do.