Fossilized Tabletop Slab with Orthoceras & Ammonites (Auction 2026-06-05, Lot 125B)

$449.75

North Africa, Morocco, Devonian Period, ca. 419.2 to 358.9 million years ago. This large, circular fossil slab is polished to reveal striking Orthoceras and ammonite specimens preserved within a richly patterned brown and warm gray stone matrix. The coloration ranges from earthy chocolate tones to soft mineral grays, enlivened by the contrasting spirals and tapering forms of ancient marine life. Both decorative and functional, this piece showcases hundreds of millions of years of natural history. It may be mounted onto custom metal legs for use as a distinctive table, or placed directly atop an existing surface as a monumental coaster or display tray. Size: 27.5″ L x 0.65″ W (69.8 cm x 1.7 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!

Provenance: private Colorado, USA collection

Condition: Professionally cut and polished on one planar face. Some scratches and minor chips to the edges. Overall great condition.