Caloplaca saxicola is a small bright orange crustose lichen that grows on rock all over the world. It is commonly called rock firedot lichen,[1] jewel lichen or rock jewel lichen.
It has short, inflated looking elongate 1–2 mm and .3-.1 mm wide lobes that have an abrupt margin at the edge, and no prothallus.[2] It lacks isidia or soredia.[2] Apothecia may be immersed in the thallus or adnate to it, with rims of thallus-like tissue (lecanorine) with orange, flat, .4–1 mm wide epruinose discs.[2] Aptohecia develop near the lobe tips. C. ignea and C. impolita are similar but bigger, and have apothecia that form near the thallus center.[2]
In California, it is one of the most common saxicolous lichens.[1] This lichen occurs over a portion of northern North America.[3] A specific example occurrence is within the northern reaches of the Canadian Boreal forests, where Black Spruce is a dominant tree.[4]