This exceptional display of the duo of Audoliceras heteromorphs ammonites sit on a stunning display of quartz crystals, which forms the matrix-bedrock. A fine opalescence shimmers throughout both specimen ammonites, contrasting gently with the suture patterns, suture palaeontology refers to these as a flowery patterning on the surface of fossil ammonites. The sutures are the growth lines of the ammonite, sutures, the fleshy muscle attachments were attached to the inner shell wall. The sutures here are an added feature of an exceptional fossilisation and preservation of the ammonite, providing a rare glimpse into the morphology of this extinct cephalopod group.
The opalescent is characteristic of this particular fossil bedrock along the Volga river, refraction of light plays a big part in the mother of pearl shimmer exhibiting an array of attractive colours. This process has been influenced by the natural nacre of the Audoliceras Heteromorph shell and by the mineralisation process that takes millions of years to develop, we're lucky to be able to see these wonderful fossils in our time. Chitin is the natural element of the shell, being the last remaining home or exoskeleton of the once living ammonite. The chitin undergoes a metamorphosim as minerals around the deposited shell, in the fossil bed region are absorbed and transform the chitin into these wonderful fossilised shells which basically transform into limestone. Permineralisation is the term used to describe the process after petrification of the ammonite animal which creates this effect. A truly unique event the naturally formed fossil, on quartz and limestone bed.