At the centre of this story is a pigment found widely in life on Earth: melanin. This molecule, which can range from black to reddish brown, is what leads to different skin and hair colours in people. But it is also the reason why the various species of mould growing in Chernobyl were black. Their cell walls were packed with melanin.

Just as darker skin protects our cells from ultraviolet (UV) radiation, Zhdanova suspected that the melanin of these fungi was acting as a shield against ionising radiation.

It wasn't just fungi that were harnessing melanin's protective properties. In the ponds around Chernobyl, frogs with higher concentrations of melanin in their cells, and so darker in colour, were better able to survive and reproduce, slowly turning the local population living there black.

In warfare, a shield might protect a soldier from an arrow by deflecting the projectile away from their body. But melanin doesn't work like this. It isn't a hard or smooth surface. The radiation – whether UV or radioactive particles – is swallowed by its disordered structure, its energy dissipated rather than deflected. Melanin is also an antioxidant, a molecule that can turn the reactive ions that radiation produces in biological matter and return them to a stable state.