High in the central Brecon Beacons, not far from the quiet village of Heol Senni, a small disused quarry cuts into green-grey sandstone, not far from the quiet village of Heol Senni, lies a small disused quarry cut into green-grey sandstone. To most passers-by, it is an unassuming feature – a slice of rock along the hillside with ruined quarry buildings, streaked with moss and fern. Yet, within those thin beds of rock, lies one of the most eloquent records of life’s first steps onto land: a fossil flora that captures the dawn of terrestrial ecosystems, and a single, irreplaceable fossil fish that swam among the earliest green riverbanks.