Angels' Money and Slaves' Lentils
The Greek traveller and writer known as Strabo the Geographer (ca 63 BC-21 AD) visited the pyramids of Gizeh which were then some 2500 years old. The pyramids are constructed of Eocene limestone full of the fossil shells of nummulites. These are the remains of single-celled animals (foraminifera) that lived on the sea-bed and secreted complexly-chambered, flat shells up to 4 cm in diameter. The fossil nummulites drop out of the limestone after weathering. Picking up examples of these fossils, Strabo was informed that they were the petrified remains of the food belonging to the workers who built the pyramids.
The main nummulite found in the limestones of the pyramids is a species called Nummulites gizehensis . This exists in two different forms, large and small, representing respectively the diploid (with two sets of chromosomes) and haploid (with one set of chromosomes) stages of the life cycle. The large form has become known as 'Angels' Money' and the small form 'Slaves' Lentils'.