Lot 22, Auction 4/12/2026: Polished Orthoceras & Ammonite Fossil Slab Table Top

$325.00

In stock

North Africa, Morocco, Devonian Period, ca. 419.2 to 358.9 million years ago. A large, circular fossil slab, polished to reveal striking Orthoceras and ammonite inclusions set within a dark stone matrix. The surface displays a dense arrangement of elongated cephalopod forms and chambered shells, creating a naturally intricate pattern, while the verso is sealed for added stability and durability. A decorative yet functional piece of deep geological history, suitable for mounting on custom legs as a table or placed on a surface as a substantial display tray._x000D_
Size: 27″ Diameter x 0.75″ W (68.6 cm x 1.9 cm)

Prehistoric ‘straight’ cephalopods include straight ammonoids called orthoceras. Cephalopod evolution began during the Late Cambrian Period. Some of these creatures evolved into semi-coiled forms, eventually giving rise to coiled cephalopods like ammonites and nautili. Straight cephalopods were among the most advanced invertebrates of their time, with eyes, jaws, and a sophisticated nervous system. These creatures were predators that swam freely using a jet propulsion system by squirting water from their bodies. They had tentacles and ink sacs, much like present-day squid. Except for belemnites, cephalopods had external shells with hollow internal chambers separated by walls called septa. A tube called the siphuncle connected the body with the chambers allowing the animal to fill them with water or air, changing its buoyancy in order to rise or drop in the ocean. Only the last and largest chamber was occupied by the living animal!

Condition: Professionally cut and polished on one planar face. Scratches and minor chips to the edges, with some uneven edges from the shaping process.

Provenance: private Colorado, USA collection

All items legal to buy/sell under U.S. Statute covering cultural patrimony Code 2600, CHAPTER 14, and are guaranteed to be as described or your money back.

A Certificate of Authenticity will accompany all purchases.

We ship worldwide and handle all shipping in-house for your convenience.