Ammonite Pair in Display Case | Madagascar

Cretaceous - Albian Stage (110 MYO) Ammonite fossils from Ambatolafia, Mahajanga Province, Madagascar.

Receive ONE, random hand selected piece, each one is hand selected for quality and each piece is unique. Comes in a 3.5" x 3.5" floating case. Picture is representative of what you may receive, however actual piece varies. The ammonite halves (mostly Cleoniceras) are polished on both sides and range in size of approximately 1-3 cm.

Ammonoids are a group of extinct marine mollusk animals in the subclass Ammonoidea of the class Cephalopoda. These mollusks, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid, and cuttlefish) than they are to shelled nautiloids such as the living Nautilus species. The earliest ammonites appear during the Devonian, and the last species vanished in the Cretaceous–Paleogene extinction event.

Ammonites are excellent index fossils, and it is often possible to link the rock layer in which a particular species or genus is found to specific geologic time periods. Their fossil shells usually take the form of planispirals, although there were some helically spiraled and nonspiraled forms (known as heteromorphs).

The name "ammonite" is derived from its spiral shape and fossilized shells, which bear a resemblance to tightly coiled ram's horns. Pliny the Elder (d. 79 AD near Pompeii) referred to these fossils as ammonis cornua ("horns of Ammon") due to the god Ammon (Amun) usually depicted with ram's horns. Many ammonite genera end in -ceras, derived from the Greek word for "horn" (κέρας).

The extinction of the ammonites, along with other marine animals and non-avian dinosaurs, has been attributed to the K-Pg extinction event, marking the end of the Cretaceous Period.