Ammonites can amaze us with their bizarrely shaped shells, which often came about close to the many great crises they suffered during the long 300-million-year life. Macroscaphites starts off as a normal ammonite rolled up in planispiral shape, then straightening out and ending with a hooklike bend. The planispiral, gas-filled part kept the shell stable in the water, while the organism itself lived in the hooklike section.

Bellerophon, a planispiral snail, is one of the best-known fossils of the Dolomites: it lends the Bellerophon Formation its name and bears witness to the definitive arrival of the sea at the end of the Permian period. This exhibit shows the snail together with a large Tainoceras malsineri, ancestor of today's Nautilus cephalopod. The large number of microfossils (calcareous algae and foraminifers) testifies to the wide variety of life forms in existence shortly before the mass extinction.

Ammonites sometimes look very similar to each other thanks to their history spanning over 300 million years. They have a planispiral shell more or less marked with ridges and tubercles. Yet they can be classified also on the basis of inner characters, so that there is never a perfect repetition. As a result, this ammonite from the Cretaceous period may always be distinguished from its ancestors.

Ammonites were cephalopods, relatives of today's nautilus, octopus and squid. They are extinct now, but used to be among the most common organisms living in the Triassic seas. There are many examples of their fossilised remains, ranging from perfectly 3-dimensional to completely flattened. The rapid morphological changes in many groups make them an important tool in rock dating. Many species in fact only lived for a few thousand years.