You have never heard of this lichen. That is the point. It was tiny – so tiny that you could look directly at it and not see it. Its branches were the height of a grain of rice, its colour was the same grey-green as the rock, its entire being was compressed into a few square millimetres of cliff face. It was the stone ghost of the coast, the living crust on the vertical rock. Its smallness made it special. The tiny coastal lichen was a specialist of the vertical cliff face – the places where the rock was bare, the wind was strong, and the salt spray never stopped. It grew only on a specific type of rock, in a specific zone of the cliff, where the moisture from the sea met the sun from the sky. It was the minimalist of the lichen world. The branches were shrub-like, branching again and again into fine, thread-like tips. The colour was a pale grey-green, blending in with the rock. The spores were produced in small, cup-like structures at the tips of the branches. It clung. It grew. It survived. The tiny coastal lichen was a pioneer of the vertical cliff, one of the first living things to colonise the bare rock. It captured moisture from the sea spray, trapped dust from the wind, and slowly, over decades, began the process of turning rock into soil. Lichens reproduce by spores and by fragmentation. The tiny coastal lichen produced spores in tiny cups at the tips of its branches. The spores were carried by the wind, landing on other cliffs, waiting for moisture to germinate. That strategy works when the cliff is stable and the rock is undisturbed. It fails when the cliff erodes and the people climb. Coastal erosion and human disturbance destroyed it. The cliffs where the tiny coastal lichen lived were soft, easily eroded by wind and wave. Over time, the rock crumbled, and the lichen crumbled with it. At the same time, people began climbing the cliffs – for recreation, for surveying, for the view. A single footstep could destroy decades of growth. The tiny coastal lichen, so delicate that it crumbled at a touch, could not survive. By the 1910s, it was gone. The last specimens were probably collected by a botanist who had no idea he was holding the final individual. He pressed them, dried them, put them in a drawer. And the cliffs fell silent. The larger lichens survived. They are tougher, more adaptable, able to grow on a wider range of surfaces. They are the survivors, the ones that kept their heads down. But the tiny coastal lichen is extinct. A few pressed specimens in a herbarium, a few fragments of its DNA, and the memory of a lichen that used to cling to the vertical cliffs, a stone ghost on the rock. The stone ghost has crumbled. The rocks are quieter than they used to be.