please ID - sponge?

[c_scherer123]

I have a pest taking over several colonies of zoos. It is purple, and tends to throw out "shoots" which break off and find a new home. It spreads quickly, and is very invasive - it is even giving my 'island' of GSP a run for its money.
I think it may be some kind of sponge. It looks like it would tear away with ease - it is soft, but doesn't peel away easily, tearing and leaving you about .5 cm of stuff in the tweezers and leaving chunks behind which grow unhindered.
I remembered reading somewhere to avoid letting air touch sponges (at least ones you want to keep), but I gave my one zoo colony a 20min breather, without fazing the pest. I gave another a freshwater dip, and swirled it for about 30 sec, but it still didn't bother the pest.

What is it and how do I get rid of it?

The purple stuff between and below polyps isn't their base, it is the pest. You can see it weaving in and out of the GSP polyps

well if it's a spunge put in direct light as spunges do not like direct light they wither and die. From my expierence.

[monocus]

watch out with killing the sponge-i had some blue sponge die on me in a move and it wiped out everything in my holding tank-lost my harliqin tusk, rabbit fish,princess parrot,3 tomato clowns,gorgonians,and all my carnations

This is why I said to move into direct light it will recede and die natural not all of a sudden. Some angels will eat sponges.

Bill