period: Upper Jurassic (163.5-145 mln years ago)
excavation site: Kraków-Częstochowa Upland
Steinkern is a form of natural fossil of an empty snail shell in a calcic rock with sand. The beginnings of the marine snails from the Pleurotomariidae family date back to early Paleozoic. Nowadays the primitive mollusca constitute a relict group living in the sea depths. They grow as big as 20 cm, are carnivorous and discharge white deterrent when in danger. What distinguishes them among other snails is the long crevice on the last volute of a shell which helps them breathe. The fossil forms of the snail can be usually found in shallow water of different periods – in Poland mainly in rocks from the Jurassic and Cretaceous epochs.
The piece comes from the collection of Polish Academy of Sciences Museum of the Earth in Warsaw.