Rhizocarpon grande is a species of saxicolous (rock-dwelling), crustose lichen in the family Rhizocarpaceae.

The surface of the thallus is thick, grey, and features a rough, cracked pattern (verrucose-areolate), varying from being closely packed (contiguous) to more scattered (dispersed).

The underlying layer beneath the crust (medulla) is white, while the border of the thallus (prothallus) is distinct and black.

[3] The reproductive structures (apothecia) of Rhizocarpon grande are black, ranging from 0.4 to 0.6 mm in diameter, and can be round to angular in shape.

These are typically flat but can also be slightly domed (weakly convex) and are often embedded in the thallus, surrounded by the cracked pattern.