Moroccan stromatolite fossil well preserved in a nice red sandstone believed to date from about 600 million years ago.These microbial fossils are one of Earth's earliest records of life. The earliest known stromatolite fossils are between 3.5 - 2.75 billion years old in the Precambrian period. The blue-green algae in these early colonies were important in creating Earth's current oxygen atmosphere. size 4.5" by 3" by 4" and weighs 1 pounds