White spike ball?

Got some live rock from a guy at work and distributed it between the lion fish tank the newly setup wrasse tank. Was afraid the wrasse was going to end up dinner lol.

Anyways i was looking at the new creatures in the lionfish tank and came across this thing.

Its a small white ball with what looks like spikes, there are what look like little legs about 3 or 4 sticking it to the rock.

Any ideas?

 

its a sponge

 

a pretty cool one at that they dont like light or air

 

I knew about the air part. Are all sponges like that with the light or certain ones, our yellow ridge sponge has gotten pretty big and he is up on the rock about 12" from the light.

Thats awesome, we didnt get alot of live rock when we did the reef tank so we didnt the cool what is that phase, lol. These things are encrusted with coralline like crazy, and so far ive seen about 20 snails, 4 feather dusters, some GSP's and alot of copepods. This exciting lol. I put a piece in the reef tank that had some grass stuff on it and a feather duster but thats all i have really seen.

 

cool i like the way u make it seem like a big adventure ,u make me wanna go flashlight my tank lol happy reefin'

 

LOL im easily amused as you can tell.

 

i go through my tank with a light for hours sometimes, lots of cool things go on when those lights go out lol