Lasallia

Lasallia is a genus of lichen-forming fungi in the family Umbilicariaceae. These lichens are recognizable by their distinctive warty, blister-covered thallus surface and their unusual attachment to rocks using only a single, sturdy central connection point. They typically grow on granite and other hard rock surfaces, where they can survive in both sunny and shaded locations. The genus contains six accepted species that are found across various continents, with some species being quite common on stone walls and cliff faces....read more on Wikipedia.