In the Arctic part of Canada, in the Grassy Bay formation, interesting samples have been found that make it possible to answer one of the pressing questions about the origin of life on Earth. These are fossils of a multicellular organism that have survived well enough to identify it as a fungus. It was named "Ourasphaira giraldae" and is clearly over a billion years old.
Previously, scientists knew that when the first plants appeared on the ancient land, mushrooms were already growing around them. This means that the minimum age of this species is 500-600 million years. However, further studies of the molecular clock showed that the mushrooms must be much older. This is the latest method based on counting the number of mutations of biomolecules in DNA, which allows you to estimate the evolutionary age of a species.
The molecular clock showed that mushrooms must be twice as old, they could very well have appeared on Earth more than a billion years ago. And now a Canadian find, the same fossilized mushroom Ourasphaira giraldae, confirms this. With the help of infrared spectroscopy with Fourier transform, chitin, which is contained in the cells of fungi, was found among the mineralized remains. And electron microscopy revealed details of the two-layer structure of the cell wall - this is precisely a multicellular creature, the oldest known on our planet.
Thus, scientists have at their disposal data on the existence of advanced multicellular life on Earth a billion years ago. This is the Neoproterozoic era, the last era in the Precambrian supereon, the time when life left the ocean on land. And the first, it turns out, this way was done by the mushrooms.