Astrobiologists supported in part by the NASA Astrobiology Institute have found evidence that structures found in ~3 billion year old (Ga) quartzite may be biological in origin. The potential microfossils were identified in Farrel Quartzite from Australia, but determining whether or not they are biogenic in origin has been difficult.

The team performed isotopic analysis of the structures, and their results indicate that the spindle-like structures were formed by planktonic microorganisms. The study also suggests that the preserved microbes were autotrophic, meaning they produced complex organic molecules using energy from light or chemical reactions.

Similar structures have been found in 3.4 billion year-old rocks from Australia and South Africa, which suggests that spindle-containing microbiota may be some of the oldest preserved examples of life on Earth.

The study was published in the journal Geology under lead author CH House.