Origin
A fossil is a rock containing the preserved evidence of once living animals or plants – in this case, the orthoceras. Fossils are found in sedimentary rocks (e.g. limestone, chalk and sandstone) as the fossil forms when the animal is buried in fine sediment (usually under water). Its soft parts rot away but any longer lasting hard parts become mineralised and turn to stone.

Orthoceras swam in many of the world’s seas approximately 470 to 360 million years ago. Their modern counterparts are squid, octopus and cuttlefish. The word orthoceras means ‘straight horn’, referring to the characteristic long, straight, conical body. Although not curled like most ammonites, orthoceras shared a similar internal structure of many chambers separated by walls called septa. The soft body parts were contained in the last open ended segment (see drawing below). These sea creatures are thought to have fed on plankton and small shelled species, grabbed by the tentacles.

Movement was dependent on the many chambered body – the animal could squirt water from its rear end to propel it forwards. By adding or removing fluid from the chambers (via the long connecting tube, the siphuncle) the animal could adjust its buoyancy and thereby swim at different depths. The siphuncle and septa lines are often clearly visible on orthoceras fossils.

Pagoda Stones
The name ‘Pagoda Stones’ arose due to the (slight!) resemblance to Chinese temples. Sizes of these animals varied from a few centimetres in length to stunning specimens of several metres. After death, the bodies would settle on the sea floor, often currents would gradually align many in one direction as sediments started to cover them.

Orthoceras fossil beds, for example in Morocco, show that these areas were either once under the sea or have been raised by continental plate movements (or both).

Orthoceras at Crystals (UK)
We have been offering these wonderful fossils to our customers since the very early days of Crystals (UK). They come from the High Atlas Mountains area of Morocco. The amount of work in the preparation of orthoceras plates is enormous – and, in truth, would not be economic with E.U. rates of pay. Each plate represents a large number of hours of careful chipping and then polishing.

Many of our sales of the larger plates are to customers looking for striking natural sculptures to place in their houses or gardens.

Ros Mason – July 2006
© Crystals (UK) Ltd. T/A Crystals Reg. No. 5056864.