The Collaborative International Dictionary of English v.0.48:

Spirifer \Spi"ri*fer\, n. [NL., fr. L. spira a coil + ferreto
   bear.] (Paleon.)
   Any one of numerous species of fossil brachipods of the genus
   Spirifer, or Delthyris, and allied genera, in which the
   long calcareous supports of the arms form a large spiral, or
   helix, on each side.
   [1913 Webster]