The Paleoarchean (; also spelled Palaeoarchaean (formerly known as early Archean)) is a geologic era within the Archaean. It spans the period of time —the era being defined chronometrically and not referenced to a specific level in a rock section on Earth. The name derives from Greek "Palaios" ancient. The oldest ascertained life form (well-preserved bacteria older than found in Western Australia) is from this era. 3,480 Ma: Fossils of microbial mat found in 3.48 billion-year-old sandstone discovered in Western Australia. The first supercontinent Vaalbara formed during this period.