The idea came from a 2012 study by researchers at Yale University, who found a rare mushroom in the Amazon called Pestalotiopsis microspora that was capable of breaking down polyurethane - the main ingredient used in plastics. Not only could this fungus live entirely off polyurethane, it could do so in an anaerobic (oxygen-free) environment that resembles the bottom of a landfill.

As it turns out, species of plastic-eating fungus are actually pretty common, and together with fellow designer Julia Kaisinger and scientists from Utrecht University in the Netherlands, Unger identified two that would be perfect for their device: Pleurotus ostreatus - aka the oyster mushroom - and Schizophyllum commune, a species that's listed as inedible in the UK and US, but is popular in parts of Mexico and India.

The device features a series of little white cups that are made from agar (seaweed-derived gelatin), starch, and sugar, and thin slices of plastic waste that have been previously sterilised with UV light are placed inside. The mycelium (or roots) of P. ostreatus and S. commune mushrooms are dropped into the cups, and as they grow, they feed off the plastic waste and nutrients in the cup walls.

"In just a few weeks, fungi begins to grow out of the pods, using the plastic to feed its development," Fiona MacDonald reported for us back in 2014. "After several months, the plastic will be completely decomposed and you’re left with nothing but an agar cup filled with edible fluffy white mycelium."

A similar scenario forms the basis for the 1971 novel Mutant 59: The Plastic Eaters by Gerry Davis and Kit Pedler:

"In the shaft leading to the [ventilation] grille a mindless, groping mass of malodorous corruption was thrusting its way silently towards the surface. Buoyed up by bubbling foam it steadily rose. Single units in an obscene abrogation of normal order divided and made two. Two became four and four, eight. Endlessly supplied with food, each unit absorbed nutrient and in a soft, ancient certainty fulfilled its only purpose - to multiply, to extend and to multiply...

"In the Coburg Street control room of the London Underground system,there was a full emergency... In a dozen tunnels, trains ground down to a halt. Hordes of terrified commuters made their way anxiously along dark, musty tunnels to the lights and safety of the next station. There were minor explosions, fires, and the failure of a million wires andcables. As the dissolution of plastic proceeded and accelerated in rate,the elegant order of the system gradually turned into complete chaos.

"On the surface, in the freezing December air, the smell of the rotting plastic began to hang permanently in the air. A cloying, wet, rotting smell similar to the smell of long-dead flesh. It filled streets , basements and factories. Traffic lights failed, causing irresolvable jams.... The breakdown of plastic spread into BroadcastingHouse.... A gas main with polypropylene seals on its pressure regulatorserupted into flame.... Plastic cold-water pipes softened, ballooned, andburst, flooding into shops, homes, and restaurants.

"Slowly and inexorably, the rate of dissolution increased; failures occurred in increasing succession until, within forty-eight hours, the centre of London had become a freezing chaos without light, heat, or communication."
(Thanks to Winchell Chung for mentioning this.)