I second the spagetti worms. White sting is what they look like and they make little tubes. No need to get rid of them. If you find that your do have aiptasia, which look like little anenomes, then I second the peppermint shrimp. I got all the rock for my
40g for free because it was covered with hundreds of aiptaisa. The peppermints took care of it. It two year I had no more problems. That was until I lost all my peppermint shrimp and added a pufferfish.