Source : Webster's Revised Unabridged Dictionary (1913)

Spirula \Spir"u*la\, n. [NL., dim. of L. spira a coil.]
   (Zo["o]l.)
   A genus of cephalopods having a multilocular, internal,
   siphunculated shell in the form of a flat spiral, the coils
   of which are not in contact.

Source : WordNet®

spirula
     n : a small tropical cephalopod of the genus Spirula having
         prominent eyes and short arms and a many-chambered shell
         coiled in a flat spiral [syn: {Spirula peronii}]