The world's oldest mushroom has been discovered in the Democratic Republic of Congo and dates back to around 810 million years ago.

Preserved in rock, the fossil fungi were found near the city of Mbuji-Mayi in a 'major' discovery that smashes the previous age record by some 350 million years.

The fungi played a key role in the history of life by helping to create primordial soil that would later allow plants to first grow on the land.

The primitive mushrooms grew in a lagoon or coastal lake, the researchers said.

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The world's oldest mushroom, pictured, has been discovered in the Democratic Republic of Congo and dates back to around 810 million years ago

'This is a major discovery — and one that prompts us to reconsider our timeline of the evolution of organisms on Earth,' said paper author and geologist Steeve Bonneville of the Free University of Brussels.

The fossilised remains of the fungal mycelium — a vast underground network of root-like filaments for extracting nutrients from the soil — were discovered in rocks dating back to between around 715–810 million years.

The ancient rocks containing the fungus are part of the collection of the Africa Museum in Tervuren, Belgium, while lies just outside of Brussels.

The fungi were found in rocks that formed in a transitional area between water and the land.

This fact, explained Professor Bonneville, 'leads us to believe these microscopic mushrooms were important partners of the first plants that colonised the Earth's surface around 500 million years ago.'

The origin of mushrooms has mystified evolutionary experts for centuries.

Their delicate nature means that their fossils are extremely rare — not to mention difficult to tell apart from other microorganisms.

'This is a major discovery — and one that prompts us to reconsider our timeline of the evolution of organisms on Earth,' said paper author and geologist Steeve Bonneville of the Free University of Brussels. Pictured, interconnected filaments formed part of a large mycelium

Around 120,000 species of fungi have been described by taxonomists — but their global biodiversity is still not fully understood.

A 2017 estimate suggests there may be between 2.2 and 3.8 million different species.

Until now, the oldest confirmed mushroom was 460 million years old.

Prof Bonneville and colleagues analysed the new mushroom in microscopic detail using state of the art scanning devices that let them identify it from its molecular composition.

They even detected traces of chitin — a very tough compound that is found in the cell walls of fungi.

The fungi played a key role in the history of life by helping to create primordial soil that would later allow plants to first grow on the land. Pictured, the fungi as seen using laser scanning fluorescence microscopy

The team also determined that the organisms were eukaryotes — meaning that their cells were complex and featured a nucleus.

For much of Earth's history, the only living things were single-celled organisms like bacteria. Today, the planet is home to much larger ones like trees, elephants - and humans. These are all eukaryotes.

In particular, eukaryotes contain sausage-shaped structures called mitochondria that supply them with energy.

Preserved in rock, the fossil fungi were found near the city of Mbuji-Mayi in a 'major' discovery that smashes the previous age record by some 350 million years

'Only by cross-correlating chemical and micro-spectroscopic analyses could we demonstrate the structures found in the old rock are indeed around 800 million-year-old fungal remains,' said paper author and geoscientist Liane Benning.

Previous mushroom fossils had been identified based solely on the morphology of their organic remains, which were extracted from rocks using corrosive acids.

'This method damages the chemistry of organic fossils and only allows morphological analysis,' said Professor Bonneville.

This, he added, 'can lead to incorrect interpretations because certain morphological characteristics are common to different branches of living organisms.'

Recent research has suggested that dry land was first colonised by primitive mushrooms.

Fungi was vital in laying the groundwork for complex plants — and later animals — to exist out-of-the-sea by beginning the processes of rot and soil formation.

Scientists generally agree that life first migrated from the oceans to the land around 500–450 million years ago, in the early Palaeozoic era.

But before any complex life forms could emerge, there needed to be nutrients on land to support them.

The full findings of the study were published in the journal Science Advances.