White worm with feelers/antennae from head


I have noticed a whole bunch of small (biggest was 0.5cm) white worms, with multilpe "legs", with thin antennae/feelers coming from the head. They are only noticed first thing in the morning. When I turn the lights on they quickly go back into hiding.
These DO NOT look like bristle worms, which I have had in the tank from time to time and can readily identify.
Tried taking a pic but my digital could not get close enough to focus on the critters. (sorry).
Any idea what they might be, and if I need do anything about their presence?