Hoplitoides Wohltmanni 202mm in size, taking the widest measurement. The Hoplitoides have an evolute whorl development of the phragmacone (shell). the discus shaped phragmacone and strong narrow or thinning keel shape is very distinctive of this ammonoid type. The outer phragmacone having been stripped away reveals the inner septa (chamber walls or divisions), the chambers were the living chambers of the soft bodied cephalopod. Each chamber increased in size as the marine mollusc developed.
Now the fossilised shell has undergone an exacting conservation treatment, using an acid preparation and finally a smooth polishing of the fossil phragmacone. This has revealed the fascinating mineralisation and colouration within, allowing the ammonoid a naturally organic appearance which is equally decorative and scientifically allowing a good study element.
Each chamber is picked out by the minerals that have been absorbed into the body cavities of the extinct marine mollusc, this mineralisation over millions of years is caused by a process of per-mineralisation. Water courses through the tissues of the fossil and by a transformation deposits mineral elements, mostly quartz based chalcedony in this instance, these minerals grow and replace the tissues within the shell eventually creating a solid limestone infill.
The Ammonoids have fascinated scholars for centuries, the Greek philosophers pondered their creation and realised they were an extinct fauna of the earth. In this part of the Ammonoidea subclass (class of Cephalopoda), one may see the appeal of these once prolific marine cephalopods. The phragmacone of the animal is produced as a hard shell or exoskeleton by the cephalopod from chitin, which is a substance of a long-chain polymer of an N-acetylglucosamine (glucosamine and acetic acid), a derivative of glucose, an important building block for the exoskeletons of many cephalopods, including the extant modern day nautili, lobsters, crabs and shrimps.