The traces were analysed and reconstructed in 3-D using X-ray computed micro-tomography, a non-destructive imaging technique. The more or less sinuous structures are tubular, of a generally consistent diameter of a few millimetres, and run through fine layers of sedimentary rock. Geometrical and chemical analysis reveals that they are biological in origin and appeared at the same time the sediment was deposited.
The traces are located next to fossilised microbial biofilms, which formed carpets between the superficial sedimentary layers. It is plausible that the organisms behind this phenomenon moved in search of nutritive elements and the dioxygen, both produced by cyanobacteria.
What did these living elements look like? Though difficult to know for certain, they may have been similar to colonial amoebae, which cluster together when resources become scarce, forming a type of slug, which moves in search of a more favourable environment.
Until now, the oldest traces of recognised movement were dated to 570 million years ago, an estimate that appeared to be confirmed by the molecular clock. Evidence of motility found in rock that is 2.1 billion years old raises new questions regarding the history of life—was this biological innovation the prelude to more perfected forms of movement, or an experiment cut short by the drastic drop in atmospheric oxygen rates that occurred approximately 2.083 billion years ago?