There were once swathes of disused limestone quarry along Kenya’s Mombasa coastline. Over decades they had been robbed of life by the region’s cement factory. Until nothing grew. Then, in 1970, Dr. Rene Haller - a Swiss environmentalist – began a series of natural experiments. He introduced new species of trees, nitrates and millipedes that could support one another in rejuvenating the infertile soil. Less than twenty years later, the land was alive.