You have never heard of this fungus. That is the point. It was tiny – so tiny that you could kneel in the leaf litter and look directly at it and still miss it. Its cap was the size of a grain of rice, its stem was fine as a hair, its entire being was compressed into a few square millimetres of forest floor. It was the litter ghost of the understory, the living recycler in the dark. Its smallness and its role made it special. The tiny forest floor fungus was a decomposer, one of the hidden engines of the forest. It grew only on the fallen leaves of specific trees – rimu, tōtara, beech – in the deepest, dampest, darkest corners of the forest. It was a specialist, a creature of the stable, the undisturbed, the places where the leaf litter was thick and the light never reached. The cap was pale brownish-grey, bell-shaped, with a tiny white fringe at the edge. The gills were white, spaced widely apart. The stem was so thin that it was almost invisible. The whole mushroom was a ghost, a whisper, a hint of a fungus. It decomposed. The tiny forest floor fungus was a saprotroph – it fed on dead organic matter, breaking down the fallen leaves and turning them into nutrients for the trees. It was a recycler, a cleaner, a hidden engine of the forest floor. Fungi reproduce by spores, released from the gills beneath the cap. The tiny forest floor fungus produced spores in tiny, white clusters. The spores were carried by the wind, landing on other leaves, waiting for moisture to germinate. That strategy works when the forest is intact and the leaf litter is deep. It fails when the forest is cleared and the leaf litter dries out. Deforestation and the loss of leaf litter destroyed it. When Europeans arrived, they cleared the lowland forests for timber and pasture. The tiny forest floor fungus, which needed deep, undisturbed shade and a thick layer of leaf litter to hold moisture, could not survive in open farmland. Its mycelium dried out. Its fruiting bodies stopped appearing. At the same time, the removal of leaf litter – for garden mulch, for compost, for firewood – stripped away the very material the fungus needed to survive. Without the leaf litter to hold moisture, the forest floor dried out. The fungus could not recover. By the 1900s, it was gone. The last specimens were probably collected by a naturalist who had no idea he was holding the final individual. He pressed them, dried them, put them in a drawer. And the forest floor fell silent. The larger fungi survived. They are more adaptable, able to grow on a wider range of substrates. They are the survivors, the ones that kept their heads down. But the tiny forest floor fungus is extinct. A few pressed specimens in a herbarium, a few spores in a core sample, and the memory of a fungus that used to grow in the darkest corners of the forest, a litter ghost on the fallen leaves. The litter ghost has faded. The forest floor is not as alive as it used to be.