What is this white stuff

[g6gang]

Notice the white stuff growing on stalk of paly. Seems to be getting larger. Peels away easily with a stick. Is kind of rubbery and not slimy to the touch. Seems to be on one stalk only. Is this a sponge? Or some other pest.

 

[Lionfish Lair]

Looks like a sponge to me.

 

[thefuz]

Did you dip the polyps? Maybe try some CoralRX or Revive?