The new winner of the oldest fossils on Earth have been discovered and dated but their survival is a real issue for plate tectonics.
The Greenland Isua stromatolites, microbe communities that lived on the sea floor, have been found in Greenland's Isua greenstone belt and these microbes are being dated as 3700 million years old. Our planet in theory being 4500 million years old.
This also suggests that life forms were already thriving only 500 million years after the planet was formed.
Don't eat the stromatolites!
The date of the stromatolites is derived from volcanic ash and tiny crystals of zircon with uranium and lead particles which are of course used in dating methodologies. The piece of rock itself is described as ancient sea floor and here is a mystery.
In Plate Tectonics theory ancient sea floor is regularly subducted down into the Mantle - so why is a bit of sea floor dating back almost to the birth of the planet still existing on the surface of Greenland? Was it subducted and then brought back up again - and if so why did it not erase evidence of the stromatolites? If sea floor can survive for 3700 million years on Greenland where does this leave Plate Tectonics?
The answer of course is regurgitation - which takes us back full circle. Why weren't the stromatolites gobbled up by the Earth's mantle never to be seen again?
Stromatolites | Society for Interdisciplinary Studies News
Greenlands plate tectonics controversy
This area remains under controversy in the scientific community because it is arguable that there were different tectonic processes, or styles, occurring in Archean times that would have affected the outcome of what we see today: a mass of very old rocks surrounded by younger rocks that have been heavily altered in some areas and are separated by tectonic and depositional contacts.
The Isua Greenstone Belt is the only place in the world that does not conform entirely to the idea of vertical plate tectonics (an idea that is still debated).
Isua Greenstone Belt Controversies | Wikipedia