Who here knows about odd greenish objects?

[FunWithFishes]

So, for about a week now I have noticed an odd green thing growing in the back of my tank on a live rock.

Since its in the back, I kinda forget about it, but today I checked it and noticed a tube growing in the middle.

So anyone have any idea what this is, and if it is friend or foe?

 

[easternreefer]

sponge. friend

 

[Palyzoa]

Looks like a sponge to me.

 

[FunWithFishes]

Thanks for the help. I looked some up, and to me, it looks like a clathrina sponge.

Does anyone know if they are good for a tank?

 

[RussiReef]

All sponges are beneficial for reef tank