The Collaborative International Dictionary of English v.0.48:

Sandworm \Sand"worm`\, n. (Zool.)
   (a) Any one of numerous species of annelids which burrow in
       the sand of the seashore.
   (b) Any species of annelids of the genus Sabellaria. They
       construct firm tubes of agglutinated sand on rocks and
       shells, and are sometimes destructive to oysters.
   (c) The chigoe, a species of flea.
       [1913 Webster]