Nummulite, << NUHM yuh lyt, >> is an extinct, one-celled marine organism with a shell shaped like a flat disk. On the inside, the shell is coiled and divided into many little chambers. Nummulites range in diameter from less than 1/2 inch (1.3 centimeters) to more than 2 inches (5 centimeters). The ancient Egyptians used nummulite shells as coins. In fact, nummulite comes from a Latin word meaning little coin. Scientists classify nummulites in a group of living things called protists.
From about 65 million to 34 million years ago, nummulites lived in great numbers in the sea. Their shells form thick layers of rock, especially in southern Asia and in the Mediterranean. The pyramids of ancient Egypt were built with nummulitic limestone.
Many scientists believe that nummulites lived with tiny photosynthetic organisms called algae. The algae may have helped produce the shells, which consist of calcium carbonate.
