Alpine lichens are the slow ones, the pale ones, the ones that grow on the boulder fields where nothing else can survive. They are the stone carpets of the high places, the living blankets on the grey rock. And there was once an alpine lichen that grew taller than any alive today – a lichen with branching stalks that rose 15 centimetres from the stone, with pale grey-green cups that formed a dense, springy mat over the boulders. It was the giant alpine lichen mat, and it is gone. Thickness and cold tolerance made it special. A 15-centimetre lichen in the alpine zone is a giant – a dense, branching mat that covered the boulder fields, holding moisture, trapping heat, providing shelter for the small creatures of the high places. Its stalks were thick and sturdy, its cups were wide and pale, its whole being was adapted to the harsh conditions of the mountain. It built the alpine soil. In the harsh alpine environment, soil is precious – a thin layer of organic matter over rock, easily eroded. The giant alpine lichen mat captured wind-blown dust, held moisture from melting snow, and added its own decaying tissue to the ground. It was the engineer of the alpine boulder field, the lichen that made it possible for other plants to grow. Its dense mats provided shelter for alpine insects, mites, and spiders. Its pale colour reflected the harsh sunlight, protecting the delicate tissues underneath. It was the heart of the alpine boulder community. Lichens reproduce by spores and by fragmentation. The giant alpine lichen mat produced spores in cups at the tips of its branching stalks. The spores were carried by the wind, landing on other boulders, waiting for moisture to germinate. It grew slowly – a few millimetres per year – and a 15-centimetre lichen might be a century old. That strategy works when the mountain is stable. It fails when the grazers arrive and the climate warms. Introduced grazers and climate warming destroyed it. European settlers introduced goats, chamois, and thar to the mountains. These animals love lichens. They ate the branching cups, trampled the mats, tore up the fragile soil. A slow-growing lichen that takes a century to reach full size cannot survive annual grazing. At the same time, the climate warmed. The alpine zone began to shrink. The giant alpine lichen mat, adapted to extreme cold, could not survive in the milder conditions that crept up the mountain. Its range contracted, then disappeared. Erosion delivered the final blow. Without the lichen mats to hold the soil, the boulder fields began to slip. The stones tumbled downhill, burying what remained of the lichen. By the 1910s, it was gone. The last patches were probably eaten by a goat or buried by a rockslide. No one knew they were the last. The smaller lichens survived. They are lower-growing, more adaptable, able to survive in a wider range of conditions. They are the survivors, the ones that kept their heads down. But the giant alpine lichen mat is extinct. A few pressed specimens in a herbarium, a few spores in a core sample, and the memory of a lichen that used to cover the alpine boulder fields, a stone carpet on the mountain. The stone carpet ghost has faded. The goats came. The climate warmed. And the lichen mat crumbled to dust.