Building Stones of Great Edifices: Great Pyramid

Foraminifera, or forams, are one of the more well known group of fossils.  Most, such as the ones in the Salem Limestone, are wee little critters but one genus, Nummulites, is notorious for the great size of the species.  Nummulites are also famous because they are the dominant component in the limestone used at the Great Pyramids.  That stone formed 40 million years ago and is part of series of limey rocks found in Egypt.

 A handful of Nummulites (from Lorraine Cassaza's web page)

These Nummulites have long fascinated visitors to the pyramids.  According to many writers, the historian Herodotus (5^th century BCE) was one of the first to comment on them. He supposedly gave the fossils their name, based on their coin-like shape.  Nummulus is Latin for coin.  But if you read through Herodotus’ Histories he makes no use of the term Nummulus and only refers generically to shells.  (One Herodotus expert I contacted wrote: “Herodotus would not have used the term 'nummulites' because it is not a term which existed in his time.”) 

A handful of Nummulites (from Lorraine Cassaza's web page)

Several hundred years after Herodotus wrote his Histories, another historian, Strabo, provided additional thoughts on the shells.  In Book 17 of his Geographica, he wrote of chips “that are like lentils in both form and size…They say that what was left of the food of the workmen has petrified; and this is not improbable.”  In Europe, where Nummulites also appear, the ideas for the fossils’ origins were equally dubious.  Botanist Carolus Clusius (1526-1609) referred to an old legend from Transylvania.  The fossils were “pieces of money turned into stone by King Ladislaus, in order to prevent his soldiers from stopping to collect them just when they were putting the Tartars to flight!"  

Such fanciful theories soon gave way to a more scientific understanding but in 1912 a new idea about Nummulites arose.  In that year, invertebrate paleontologist Randolph Kirkpatrick self-published his The Nummulosphere: an account of the Organic Origin of so-called Igneous Rocks and Abyssal Red Clays.  It proposed that Nummulites were responsible for the formation of all rocks, whether igneous, extraterrestrial, or sedimentary. In a follow up to the book, he wrote “The book was, I believe, regarded by some as a symptom of mental derangement on the part of the author.”  He didn’t disagree and added that the earlier book lacked evidence, which he would now possessed.

 (From Wikipedia)

According to researcher Lorraine Casazza, Nummulites are some of the largest single-celled organisms ever.  They were able to reach their great size by growing complex shells, which leads to a large surface area relative to volume.  She writes that the most accepted reason for gigantism is that algae live inside the foram and are able to photosynthesize, which facilitates rapid shell secretion.  Her research focuses on whether this hypothesis is correct.  Judging from the long term interest in Nummulites perhaps they are the most curious aspect of the pyramids.