What do marine worms look like?

Marine worms come in many different forms, depending on which phyla they are from.  There are segmented worms that look much like earthworms; there are worms that look like beautiful fans waving in the water.  There are long and thin worms, flat and wide worms, short worms, and worms in tubes.  Worms also come in a range of colors, from brightly colored worms to ones that are dull looking.