Strange white growth on sump glass, is this a sponge?

[Jrod4]

Noticed this growing on a couple spots in my sump next to the skimmer, anyone know what it is and should I get rid of it?

http://postimg.org/image/rsl8np6df/

http://postimg.org/image/rsl8np6df/

[thegrun]

Yes, it is a sponge

[YoungREEFA]

Pineapple sponge

[thegrun]

It's a sponge but not a pineapple sponge.

[Jrod4]

Is this good or bad? Should I leave it be?

What do sponges grow off of? Do they prefer darker areas?

[thegrun]

It's fine either way.

[amutti]

It's good in the sense that it does no harm and filters the water. If you have a lot of them you could say it's bad because it probably indicates that you have high nutrients in the water.

[YoungREEFA]

I assumed since i couldnt view the picture :)