About 50 million years ago, the area that is now known as Egypt was covered with an ancient sea. At the bottom of this sea were nummulites, a genus of small seashells made of calcium and carbon. Over millions of years, these creatures would die and stack up on the ocean floor, eventually creating limestone. Fast forward to human civilization and we see this:
This image comes from a limestone quarry near Cairo – the same sort of quarry that the ancient Egyptians used to build the pyramids and other structures of that great civilization. In other words, there is a homogenous mix of fossils that can be found all throughout one of the 7 Great Wonders of the World; the Egyptians owe much of their incredible accomplishments to deposits laid down by dying marine creatures over 50 million years ago.