positive its not a brittle star, this guys just died today, he began turning a clearish white, and fell out of the rock. I assume he died because of the ammonia level. My tank is still new, its only been cycling about a week. But today I spotted two more coming out of totally different rocks...I am really curious about these guys, can somebody help!?
I'm not sure what type of worm it is. I'll see what I can find - have you been able to see it's "head"? If so, that may be a help. Here is a nice site - if you click on Family Key (same with the Genus section), you then answer questions to help analyse the family of worm you have. If you are unsure of what the question is/what the morphology means, simply click on the question and it will show you. Polychaete Identification.