They sound like copepods to me. If they are then you dont really want to get rid of them. In fact the more you have the better. Copepods are very beneficial to your tank and you can even buy them on this site under inverts and shrimp.
Why would you want them? I dig them out of the sand and flush them. They just keep coming back and theyre getting annoying. I dont even know how to get the ones in the rock out.
I have these brown worms that live in sand and sometimes rock in my reef tank. There body lies beneath the sand and they have little brown apendages with tiny black spots that spread out above the sand and collect any fallen food. I didnt have a problem when there was just 1 or 2 of them but now...
With the camera I have now you cant see them at all, they are very small, about the size of a strand of hair, but they get longer and I see more strands coming out of the central spot.
In my sand there are these long stringy brown things coming out. They are very skinny , and brown with little black dots. They look like they start in one sopt and branch out from there. Anybody know what they are?