The thallus of Nevilleiella marchantii spreads 1–3 cm wide, with distinctive, almost spherical, pustule-like formations that give it an appearance resembling a bunch of grapes.

The species epithet honours Western Australian botanist Neville Graeme Marchant, who assisted the authors during their field research.

[1] In 2017, Kondratyuk and Jae-Seoun Hur transferred the taxon to the newly circumscribed genus Nevilleiella, in which it is the type species.

The areoles themselves are highly varied in form, ranging from convex and warty to spherical, and are coloured yellow-brown to orange-brown, occasionally with a whitish pruina.

They initially emerge immersed within single areoles and later develop a thalline margin and a concave disc, which becomes flatter as the apothecia mature.

[1] The hymenium (the fertile, spore-bearing layer) of Nevilleiella marchantii can reach heights of 60–75 μm and is often characterised by golden-coloured asci and ascospores.