From ReefKeeping, Dr. Shimeck

The white feeding tentacles of a terebellid or spaghetti worm always radiate from a burrow, tube opening or hole. These tentacles collect food particles from the surface of the sediment and convey it back to the worm’s mouth.
Look here:
http://www.reefkeeping.com/issues/2002-06/rs/index.php

Also look at this picture:
http://www.reefs.org/hhfaq/worms/cir...m_guy.jpg/view
Really looks close to the same picture you posted.