Circinaria arida (pebble ball lichen) is a 0.5–6 cm, light olive-brown crustose lichen that grows on rock, often like a cluster of little light brown to olive balls growing on pebbles, in the southwestern deserts of North America.

[1] It is also found in Eurasia, and arid parts of North America from the southern Great Plains and Midwest to California.

[1] Each areola has a single sunken black, dust covered (pruinose) fruiting body (apothecium) with a white rim.

[1] A thin strip of prothallus sometimes is at the outer edge, forming a narrow dark zone (fimbriate).

[2] The similar Aspicilia desertorum has a white pruina (dusty coating) on the apothecia.