Id Help with zoanthid irritant

[Duke]

yesterday I noticed a few of these zoo's closed up.. today this is what it looked like, seems like a sponge or possibly a macro algae of some sort taking over, but it literally appeared overnight and its knocking out my zoos, any ideas?

 

[Duke]

tried a fresh water bath but all that did was kill a bunch of pods and a few mini starfish.

 

[Salty Cracker]

Looks like a type of sponge. 

 

[unibob]

Use a scalpel to cut them off zoas. Have had this happen on wild colonies. They love it once they get free.