Need an ID on this worm...

[stemonia]

Take a look at these worms? I just noticed them on a couple of the rocks in my reef. They seem to have popped up out of nowhere and there are a lot of them. I've popped a couple of them off the rocks and they are stony in structure. Are they dangerous? If so, is there anything I can add to the tank that might prey on them?

 

[luke33]

There a type of snail, a verm...somethin. They put out a web to catch food. There s mixed feelings about them. I have some and i keep them in check by crushing them if they get close to any corals. I would rather do without, but what can you do. I do hear they can get waaay out of hand if your not careful.