Aspicilia pacifica (pacific sunken disk lichen) is a white to grayish, brownish, or ocher crustose areolate lichen that commonly grows on siliceous rock or basalt along the seashore and in higher coastal mountains of California and Baja California.[1] [2] It has numerous small (0.1ā.8 mm), round to angular apothecia toward the middle of the thallus, with concave to flat black discs that are sometimes lightened with white pruina.[2] Lichen spot test on the cortex and medulla are Iā, K+ yellow to red, P+ orange, and Cā.[2] Secondary metabolites include much stictic acid, and some norstictic acid.[2]