The Collaborative International Dictionary of English v.0.48:

Nautiloid \Nau"ti*loid\, a. [Nautilus + -oid: cf. F.
   nautilo["i]de.] (Zool.)
   Like or pertaining to the nautilus; shaped like a nautilus
   shell. -- n. A mollusk, or shell, of the genus Nautilus or
   family Nautilidae.
   [1913 Webster]