No one knows when the very first life on Earth appeared – though what little evidence scientists have indicates that life was present not very long after our planet formed.

Fossil hunters are continually scouring the globe for rocks betraying signs of even more ancient life forms, and controversy reigns over claims of the earliest evidence for life.

One such fossil hunter is Nora Noffke, a trace fossil sedimentologist at Old Dominion University in Norfolk, Va. Noffke and team recently found rocks in South Africa with evidence of cyanobacteria dating from 2.9 billion years ago, which is the oldest confirmed evidence of these life forms. Cyanobacteria is a type of single-celled bacteria – still thriving on the Earth today – that gains its energy from sunlight, through photosynthesis.

The Earth itself is thought to be about 4.5 billion years old. [ LIVE SCIENCE ]