ammonoid

From the scientific name Ammonoidea.

ammonoid (plural ammonoids)

1. An extinct cephalopod of the subclass Ammonoidea (including ammonites).
   • 2017, Mark Carnall, The Guardian, 9 August:

     Although the extinct externally shelled cephalopods ammonoids have an extensive fossil record, their soft tissues are very poorly known and, like extinct and living nautiloids, they are largely presumed to not have possessed an ink sac.

ammonoid (comparative more ammonoid, superlative most ammonoid)

1. Characteristic of an ammonite