Foraminifers (Foraminifera)

Foraminifers are unicellular organisms which protect themselves by forming calcareous shells. Many foraminifers are confined to certain rock layers, which makes them good 'index' or 'guide' fossils: a fossil species which can be used to determine the age of a certain deposit. Orbitoides is such an index fossil. This ‘small coin’ with a diameter of only a few millimetres only occurs in rocks of late Cretaceous age. The same holds true for Siderolites, the 'little star'.   home | back