A secret world lies beneath our feet.

Hidden under the ground, millions of fungi are in communication. It is a world few know about and even fewer understand. 

Now, for the first time, scientists are on a mission to map this "ancient life support system". Over the next 18 months, "myconautsAn unofficial term for the local experts who will collect the fungi samples. They are named after mycology, the study of fungi. " around the world will collect 10,000 samples, building a global map of fungi hotspots.

There is no doubt: mushrooms are having a moment. This week, mycologistA biologist who studies fungi.  Merlin Sheldrake won a major prizeSheldrake won the Royal Society Science Book Prize and £25,000.  for his debut book Entangled Life, which tells the story of fungi.

Sheldrake, a rising star in the fungi world, is enchanted by what scientists call the wood wide web. He has dedicated his life to studying hyphae, the tiny threads of fungi that extend through the soil and weave into the tips of plant roots. 

Together, the hyphae form a net called a mycelium. The fungi siphon off carbon-rich sugar from the trees. In turn, the plants acquire nutrientsSubstances that plants and animals need to live and grow. The six essential nutrients our bodies need are vitamins, minerals, protein, fats, water, and carbohydrates. the fungi have taken from the soil. Incredibly, plants can even use the network to redistribute nutrients and send warnings about attacking insects. 

For Sheldrake, the wood wide web "easily qualifies as one of the wonders of the living world". The total length of the fungal network in the top 10 centimetres of the soil alone is an astonishing 450 quadrillionOne quadrillion is one followed by fifteen zeroes.  kilometres - half the width of the galaxy. There are an estimated six million fungal species worldwide, but we only know about less than 10% of them.

Fungi predate humans by millions of years. Without them, there would likely be no plants on land, and maybe even no people.

But increasingly, humans are putting this system under threat. Agriculture, fertilisers, deforestation and urbanisation are all destroying vital fungi. Meanwhile, most conservation efforts focus on what we can see above the soil. 

Ecologists warn we are missing our opportunity to save an invaluable ally in the fight against climate change. Worldwide, fungal networks lock an estimated five billion tonnes of carbon dioxideCarbon dioxide is a colourless gas formed during the combustion of any material containing carbon and is a significant greenhouse gas.  in the soil. Releasing it into the atmosphere would have devastating consequences. 

For centuries, humans have been awed and horrified by fungi in equal measure. We use them to make blue cheese, bread and medicines, but they are also a staple of horror stories. Few readers could forget Stephen King's short story Grey Matter, about a man who drinks "a bad can" of beer and slowly undergoes a terrifying metamorphosisA complete transformation or change of appearance and structure.  into a fungal creature.

Talking plants, too, once belonged only to the realm of science fiction. From the sentientAble to perceive or feel things. venus fly trap in the Little Shop of Horrors to Groot, the friendly but monosyllabicA person or thing that says very little, usually only one word. The tree Groot can only say his own name. tree in Guardians of the Galaxy, talking plants have entertained millions across the world.

Now, perceptions are beginning to change. Every day, scientists are learning more about how fungal networks are key to communication underground. For many mycologists, the idea of talking plants does not seem so ridiculous at all. 

Yes: The ability of plants to share information is nothing short of miraculous. Trees warn each other of threats and share nutrients. We must do everything we can to protect this network before it is destroyed. 

No: Plants and fungi do not have brains. They do not have the intelligence and emotion of humans or even certain animals. 

Or... It is short-sighted to think about language only in the way we use it. It might be absurd to suggest plants can speak, but the way they share information is marvellous - and not something to ignore.