The species has a unique life cycle in which it starts as a juvenile non-lichenised fungus before forming a fully lichenised thallus.

[3] The thallus of Acarospora stapfiana is variable in form, ranging from areolate (cracked into small pieces) to subsquamulose (somewhat scaly), and often appears as a contiguous structure.

the lichen's cortex, the outermost protective layer, is 45–70 μm thick and composed of a tightly packed cellular structure.

The asci, the spore-bearing sacs, are clavate (club-shaped) and contain over 100 ascospores each, which are roughly spherical to broadly ellipsoid, measuring 3–5 by 3–4 μm.

[4] The presence of this compound causes the lichen thallus to fluoresce an orangish colour when lit with long wavelength ultraviolet light.

Over time, it consumes the host's tissues, replacing the distinctive orange thallus of Caloplaca with its own yellow lichenised form.