Lichen on granite.

Sierra de La Cabrera from behind Canchos Gordo and Largo, looking towards Cancho de La Bola.
I only ever see this lichen on the cooler and more moisture-laden northern facing granite boulders and cliffs. In Cornwall, where moisture is all around, this lichen doen't have a favourite face and it therefore happily covers whole boulders.
From memory, I think I ate my packed lunch here. Usually I wait until I reach my picnic table behind the far peak seen here. But I stopped too often to take photos and hence I was behind schedule if I wanted to get to Valdemanco in time catch the last bus back!