Spaghetti Sponge? Beneficial or Detrimental

If you look to the left of this picture you can see the white tentacles of what I believe to be a sponge sticking out on the left there is white mass in a crevice that looks to be related. Found it in a rarely looked at crevice in the tank.

Is it good, is it bad? Keep it, scrub it?

Thanks.

 

It's fine, a more unusual growth form but fine. I doubt it will become invasive.

 

Thanks my six year old actually found it. He keeps a lighted magnifying glass near the tank so he can make observations (It's how I get him to practice his writing) and he discovered it.

Upon further review I have a lot of these hidden in the recesses of the rock.

 

just leave them. I have several throughout the tank as well. They are filter feeders

 

That makes me feel a bit better. Though if these things were gold I could retire tomorrow as I have ton ;D