Description: Orthocerid Orthoceras sp. Ordovian Atlas Mountain Region Morocco Approx: 450 Million Years Old

On offer is a polished specimen of Orthoceras sp. preserved in a hard black limestone. It's name derives from its long straight shell or orthocone. This tapering cone grows as the organism grows, becoming wider at the head end. In life the organism was squid-like with a ring of tentacles ready to catch its prey. They were very successful with a range from the Ordovician to the Triassic period (approx. 500-200 million years)...

These would evolve into the coiled nautiloids that still exist today. In a similar manner evolution took this design and created firstly the coiled Goniatites and finally the vey familiar Ammonites...

Their reign lasted for approximately 300 MY ranging from about 500 to 200 million years ago.

When dead they would settle in the bottom sediments and get slowly buried. The soft parts would soon rot leaving only the hard calcitic cone shaped shell. The sediments filled the 'shell' and hardened. The calcite often crystallised preserving the sequence of growing chambers and often the long straight gas exchange tube or Siphuncle. This allowed to organism to float, rise and fall just like a modern submarine. These are for novice collectors or just lovers of nature's amazing organic art forms.

Supplied with a small perspex stand and an information card...