Something weird (really) growing on my corals

Can't figure out what these are, but from the pictures I've seen of the latter, it doesn't exactly look like spaghetti worms, but whatever it is, is beginning to choke out my Green Star Polyps little by little. I took this pic right after I turned on the light so the polyps would stay retracted and the culprit could be seen more easily. Whatever it is, it's the white stringy looking stuff at the bottom left of the colony. It's also beginning to grow at the base of one of my Hammer Coral frags on the other side of the aquarium.

 

well, i cant say ive ever seen that before, but is there anyway to scrape it off? is it like a worm, does it retract into anything when touched?

 

Looks scary. I hope someone can id it for you.

 

I did scrape what I could off (that's the "Before" pic). I rinsed/dumped/repeated several times before putting it back in the tank. I hope it isn't something that I just caused to spread faster.

It doesn't move or retract when touched, so I'm out of ideas. A few people have suggested it's some type of sponge, but it doesn't look like any type of sponge I've ever seen.

 

you must have replied right as I did. You're the third to say it's a sponge so far, so maybe that's what it is. Any idea what type or how to control it?

 

you would me amazed to learn about all of the biodiversity in the worlds oceans.

 

Any chance it's a macro algae?
From the pic it has a similar appearance to nuisance macro that I have in my main tank, and I'm unable to get completely rid of it. Even my power blue won't touch it. It's a very firm plant, spikey and with curled branching.

 

The only thing I have found to get rid of that type of sponge it to spray it off with high pressures fresh water. You may or may not loose the coral but if you don't do anything your going to loose it for sure.

 

I don't know what it is but---could you frag the GSP and just get rid of the rest?