Most species in the genus are crustose lichens that grow on rocks in open and arid places all over the world.

[5] Species in Acarospora may be shiny as if covered with a glossy varnish, or dull and powdery looking.

[3]: 216  They may grow in crustose forms like a warty surface (verrucose), like cracking-up old crust of paint (rimose), like a bunch of "islands" in a dry lake bed (areolate), like the flakes of cracking up paint are peeling up at the edges (sub-squamulous), or like the flakes are growing over others like scales (squamulous).

[2] Sometimes the squamules may be elevated with expansion of the mycelial base above the substrate ("gomphate"), or aside on "stems" called stipes, which are usually about usually half the diameter of areole.

[2] They may or may not be covered with a powdery-looking surface (pruinose), which when present, may make them appear lighter in color, to almost white.

[3]: 216  The apothecial disc is round to squished and irregular, and ranges in colors: black, brown, red, or yellow, or in-between.

Spores are colorless, spherical to ellipsoid, and range from tens to hundreds per ascus.

Other species included by Massalongo in his original conception of the genus were A. chlorophana (now Pleopsidium chlorophanum), A. oxytona, A. cervina, A. smeragdula, and A. veronensis.