Ammonoids are extinct, typically coiled-shelled cephalopods composing the subclass Ammonoidea. They are more closely related to living octopuses, squid, and cuttlefish than they are to nautiluses, whi
A variety of ammonite forms, from Ernst Haeckel's 1904 Kunstformen der Natur (Art Forms of Nature)
Fossil of Parapuzosia seppenradensis, one of the largest known ammonites
Oppelia in association with its aptychi plates
A nautilus is any of the various species within the cephalopod family Nautilidae. This is the sole extant family of the superfamily Nautilaceae, suborder Nautilina, order Nautilida, and subclass Nauti
The first and oldest fossil of chambered nautilus displayed at Philippine National Museum.
Nautilus half-shell showing the camerae in a logarithmic spiral
Section cut of a nautilus shell