Hi Dennis,
I believe the name quill worms refers to marine annelids (segmented worms) of
the genus Branchiura.  They have a long, slender body, and the posterior half
has a dorsal and a ventral row of long filamentous gills, which make the whole
animal look very much like a feather.
Another group, not to be confused with these, is the sea quills or sea pens,
which also look like feathers.  However, these are not annelids, but colonial
coelenterates (relatives of corals).
Paul M.