Need ID on this black sponge thing!

[aquajosh]

I picked up some new liverock and this thing came on it, it seems to move from time to time and looks to have an opening like a mouth or something.

 

[greenbean36191]

[welcome]
It appears to be a tunicate. They're harmless filter feeders.

 

[aquajosh]

Thank you just wondering if it was bad or not.