In my tank there are these worm like tentacles growing out of the LR. They are white with horizontal black stripes. They will also wrap around bryne shrimp if it comes in contact. What are they, and are they harmful??
Like bang said its sounds exactly like a spaghetti worm. They are very beneficial in maintaining your sandbed and an all around great clean up critter.
Brittle Star, now that may be. Do they stay in the rock and only put out there tentacles? I wish I had a better pic. When you look close, they are rough looking. Do you have a pic? I've been searching spaghetti worms and they are definitely not that.
I have some of those in my tank too they get pretty big they do look like bristle stars with their tenecales sticking out of the rock. But they are not bristle star they often times get mistaken for it. I went to a local fish store of mines they told me its some type of tape worm cause they have it too. It comes and goes just don't let it get too large.
Moondogg
Oh ya, you got brittle stars. I can't tell the size yours are from the picture but they don't get much bigger than 1 1/2 inch long tenticles. I have hundreds in my tanks. You won't see the whole star ever they sit in the rock moving the tenticles catching whatever food drifts by.