Nummulites are protists from the phylum granuloreticulosa, and the class foraminifera,
also called foraminiferida. What does this mean? Granuloretuculosa means that they
are cells that fuse to form networks of cells. Foraminifera means it has a "test", or
internal skeleton with pores on the outside, through which it feeds with reticulopodia, which
are much like the pseudopods of amoebas but are smaller and more hair-like. Nummulites start
out in the center adding a new larger chamber in a spiral pattern, creating a disc-shaped test.
Many nummulites can be found in the lime stone of northern Africa and Mediteranean areas.
Nummulitic limestone was used in the construction of ancient Egyptian monuments, such as
the pyramids. Nummulites were named for the latin word "nummulus", or coin. They were
probably named thus because of how it resembles a coin. I have heard that in ancient Egypt,
they may have been used as currency, but I cannot confirm this. Some scientists speculate
that it may have had algae living inside in a symbiotic relationship.
About this specimen
This is a nummulite from around the Eocene and Oligocene periods 55-34 million years ago,
found in the Mediteranean sea in Greece. It's just over an inch at about 30 mm in diameter,
which is pretty big for a protist.