The Collaborative International Dictionary of English v.0.48:

natica \nat"i*ca\, n.; pl. naticas, L. naticae (-s[=e]).
   (Zool.)
   Any one of numerous species of marine gastropods belonging to
   Natica, Lunatia, Neverita, and other allied genera
   (family Naticidae.) They burrow beneath the sand, or mud,
   and drill other shells.
   [1913 Webster]