Thick 5.25" Phylloceras Ammonite Fossil (Half)

This is a thick, 5.25" wide cut and polished Phylloceras ammonite from Mahajanga Province, Madagascar. It has been agate replaced, and many of the internal chambers are lined with calcite crystals.

Ammonites were predatory mollusks that resembled a squid with a shell. These cephalopods had eyes, tentacles, and spiral shells. They are more closely related to a living octopus, though the shells resemble that of a nautilus. True ammonites appeared in the fossil record about 240 million years ago. The last lineages disappeared 65 million years ago at the end of the Cretaceous.

Phylloceras sp.
Ambatolafia, Mahajanga Province, Madagascar
5.25" wide
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