[2] They are sometimes called kidney lichens, named after the characteristic kidney-shaped apothecia that they produce on the lower surface of their lobe tips, which often curl upwards and thus are visible from above.

These features, along with the presence and nature of reproductive structures (soredia, isidia), are key characteristics for species identification.

All Nephroma species contain cyanobacteria from the genus Nostoc, which not only provide products of photosynthesis but also fix nitrogen from the atmosphere, making it available to the lichen.

[6] Research has shown that the Nostoc partners in Nephroma fall into two distinct genetic groups that correlate with the lichen's lifestyle.

This pattern holds true across wide geographic areas – specimens of the same Nephroma species collected from different continents often contain nearly identical Nostoc strains.

[6] A 2011 phylogenetic study of Nephroma species in Macaronesia (the Azores, Madeira, and Canary Islands) revealed evidence of recent evolutionary radiation and neoendemism in the region.

The research suggested that Macaronesia may have served as a source for subsequent colonisation of continental areas, with evidence of recent dispersal events from the islands to Western North America and the Mediterranean Basin.

[10] Broader evolutionary studies have revealed complex patterns in how Nephroma species develop and maintain their symbiotic partnerships.

This suggests that the evolution of different symbiotic forms in Nephroma was not a simple matter of gaining or losing a green algal partner.

This pattern holds true across continents, suggesting that these specific partnerships evolved early in the genus's history and have remained stable over long periods.

[12] Nephroma arcticum is called kusskoak by the Yup'ik of Alaska, and it is traditionally eaten after being boiled with crushed fish eggs.