Centuries after the extinction of all animal life on Earth, an expedition of alien archaeologists visited the planet. Amidst a huge amount of digital garbage, produced during decades by the human race, a collection of badly preserved images caught the explorers' attention. At first, they thought it was a representation of multiple gods of a polytheistic religion, or a collection of self-portraits, a habit cultivated by humans to generate content on their social networks. As the restoration work on the images progressed, the archaeologists reached a consensus: they were a kind of digital currency, used for diplomatic negotiations.