worm

Hello. So. My tank has been established for a little over 3 months now and for the last week I've noticed this dang worm thingy. I can't see it when the lights are off, but once the day time lights come on I notice something moves quickly then hides. After a while I see it peek it's "head" out...

What is this???? About the size of a nickel Disappeared when I turned lights on.

Greetings! So I am fairly new to salt water aquaria -- I kept a planted freshwater for a few years -- and things are going pretty well so far. A short time ago though I discovered a few new "guests" in my tank. They look to be small tendrils/worms encased in sand tubes, which based on a bit...

I just got home from work and wanted to check the tank out before I go to bed and noticed this wierd looking worm. Can anyone tell me what it is and if it's good or bad?