ammonoids are a group of extinct marine mollusc animals in the subclass ammonoidea of the class cephalopoda.

although amazing ammonites ammonoidea ammonoids ancient animals cephalopoda chambers class closely coleoids commonly creature cuttlefish dividing excellent extinct form forms fossil fossilized fossils found general genus geologic group helically index joint jurassic layer link living marine mollusc molluscs more nature nautiloids nautilus nonspiraled octopuses old oldest outer particular period periods phragmocone planispirals possible referred related rock separate septa shape shell shelled shells siphuncles some species specific spiral spiraled squid subclass sutures take time usually wall walls