Student, step out faster, for oysters wait for us in the field, and the Jurassic ammonite waits for us in the field, the Vraconian belemnite, the Lutetian nummulite

The opening of a palaeontological song composed by students of the Moscow Institute of Geological Prospecting named after Ordzhonikidze in the 1950s.

Oysters: massive, rounded-pentagonal calcareous shells.

Ammonite: the shell of a cephalopod mollusc.

Belemnite: an arrowhead-like carbonate formation inside the body of the eponymous two-gilled predator.

Nummulites: giant single-celled organisms.

Jurassic: the second period of the Mesozoic, 201-145 million years ago.

Vraconian: a geological horizon of the Albian stage, 113.2 million years ago, in the lower division of the Cretaceous system, named after the locality of La Vraconnaz in Switzerland.

Lutetian: a stage of the Eocene widespread in Western Europe, 46.8-41.2 million years ago, named after the ancient settlement of Lutetia, on whose site Paris now stands.