This is interesting and important but fun fact, maybe not the first case of 2 billion+ yr old microbes. There were microbial organisms found in a mine in Minnesota coming from 2.6 billion year old rock and they suspected they were coming from water trapped when the rock, banded iron formation, formed in an ancient ocean. IIRC there were two bacteria - one that eats sulfur and excretes iron, and one that eats iron and excretes sulfur.

Soudan Mine in northern Minnesota. Great tour.

https://www.twincities.com/2008/12/22/soudan-mine-studied-for-bacterial-life/