A slightly ghost-like structure floats gently above Parc Guillemin. Yet, this ethereal form comes from the underground since its creation is based on the cast of six tunnels of abandoned molehills. Emerged and brought to light, this network offers an overview of the labyrinths that run under our feet some 40 centimetres deep — of their magnitude too, brought back to a human scale. A monument to moles, the queens of the earth, which they ventilate in partnership with earthworms, who themselves literally produce the soil.