Growth on LR! What is this!

I noticed some weird growth taking over a piece of LR and wanted to know if i need to worry or do something or if it's a good thing. It's hard to see in my picture so i'll describe it aswell.

It's soft , dark purple in color, translucent, looks like a skin over the LR and has peaks comming off the tops with little holes at the top. I have no clue but could it be a sponge or somthing like that. i would also guess some sort of little critters live in there becasue of all the little hole going into it.

 

It looks like tunicates to me.

 

hmmmm....is that something i want in my reef or something that needs to be dealt with?

 

That's what I thought. Or possibly some type of sponge.

 

Harmless filter feeders.....actually they're kind of neat looking IMO

 

i think it is tunicate