The Collaborative International Dictionary of English v.0.48:

aplacophoran \aplacophoran\ n.
   1. one of the aplacophora; a deep-water wormlike mollusk
      lacking calcareous plates on the body but having fine limy
      spicules on the covering mantle.

   Syn: solenogaster
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

aplacophoran
    n 1: deep-water wormlike mollusks lacking calcareous plates on
         the body but having fine slimy spicules on the covering
         mantle [syn: solenogaster, aplacophoran]