Ok so I have noticed these small brown tubes on the dividers of my 75gal. tank. They are about 3mm to 7mm long and about 1/2mm thick. I thought they might just be an anchor or "root" of a thin stringy algae that has been growing in the tank. I was wrong when I took a closer look and noticed a tiny worm a little thicker than a hair reaching out of its tube and then quickly retreating into its lair. I was wondering if the experts, maybe oddball since he is a genius could try and explain this for me. I will try to get some macro shots on my digi later and post them. I don't think they are harmful since my fish have been doing great and look stunning.