The Isua Greenstone belt is between 3.9 and 3.7 billion years old and is a heavily metamorphosed seafloor, which includes both mafic and sedimentary material. Although highly controversial, there are several lines of evidence which imply the presence of life at the time the belt formed.
The inclusion trail of this garnet contains carbon material with a carbon isotope ratio, which implies the presence of life. This is by no means conclusive, but is highly intriguing.
This sample weighs 10g. The photograph is of the object offered for sale.