How old is your Sand Bed?
I had them in both my old 55 and more recently my 20 nano. They can become rather prolific, so my opinion is: stop them while you can.
Personally speaking, if I see even one of he little buggers in my “newer†120 (est. August 2008), they will become drafted into the "NFL".
Not.
For.
Long.
But they shouldn't be harmful, if you opt to keep them. Some folks like them. They're just a little creepy looking en masse.