A colorful look at 3.5 billion years of stromatolites, peculiar structures produced by primitive life forms that lived over vast spans of geologic time. At once diverse, attractive, and sometimes puzzling, fossilized stromatolites are found worldwide in sedimentary rocks-often presenting striking patterns-where they grew in ancient bodies of water that covered parts of the earth billions of years before the dinosaurs. This reference presents a basic, nontechnical account, along with 636 beautiful images of these most ancient of Earthly collectibles. Stromatolites, and the cyanobacteria that produced most of them, were responsible not only for the fossils themselves, but also, more importantly, for the introduction of free oxygen into the planet's atmosphere. Covering a diverse variety of stromatolites and the geologic objects that can resemble them, this book is a delight for stromatophiles as well as those curious about the early Earth.