nummulite
/ˈnʌmjəlaɪt/
noun
- A fossil of a large, coin-shaped single-celled organism that lived in warm seas millions of years ago.
- The limestone cliffs were full of nummulites, showing the area was once underwater.
- Nummulites are often used by geologists to date rock layers.
- She collected nummulites during her trip to the Egyptian desert.