Help ID a growth

[coppertop]

I apologize if Im in the wrong forum..I am new to the marine world...pls move if needed.

Can anyone id this growth on the underside of the live rock? It's growing in size. I dont know if its plant or animal.

http://www.facebook.com/photo.php?pid=932562&l=c69d4&id=553690820

 

[CadetMKultra]

tunicates. animals. filter the water. a good thing. If it's on the underside of a rock, you can be pretty sure it's an animal, as plants need light.

 

[greenbean36191]

Looks more like a sponge than a tunicate.

 

[KurtsReef]

I have always considered that a sponge

 

[Atarax]

sponge