Gold cobblestone lichen

Pleopsidium flavum is a bright yellow radiating crustose lichen with lobed margins found on vertical rocks at higher elevations. Crustose lichens differ from the leprose lichen by having an upper cortex and algal cells that are located directly beneath the cortex. An underlayer of fungal hyphae, the hypothallus, is present on some species of crustose lichens. These fungal hyphae are usually what attach the thallus firmly to the substrate.