Alright, just found out that ragworms and nereids are the same thing. I also just found out that ragworms make cocoon-like webbing to catch food. Well I have that webbing on my live rock. I thought is was die off rotting away, but this is too coincidental. I think it can be 90% narrowed to a ragworm or nereid. What precautions, if any, should I take? I'm leaning towards find it and destroy it.