It challenges the imagination to think of nearly identical microbes 16,000 kilometers apart in the cracks of hard rock. ~ American geomicrobiologist Matt Schrenk
Probing mineshafts, wells, and drilling rigs that run kilometers deep, in locations ranging from the Arctic Circle to Antarctica, including the benthos in between the poles, has repeatedly revealed the same 19 species of microbes all around the world.
There seems to be a core group of microbes that appears again and again in all of these environments. ~ American microbiologist Rick Colwell
Many of the “everywhere” microbes have been found in serpentine minerals, which form under the geophysical conditions that may have prevailed when life on Earth originated. These hardly primordials may have been transported around the globe by plate tectonics, or perhaps they convergently evolved, or a bit of both among them all.
There seems to be a commonality of colonisation of the subsurface of the planet. ~ Canadian geologist Barbara Sherwood-Lollar