Cobalt Crust

Cobalt crust (Terana coerulea) is a distinctive crust-forming basidiomycete fungus in the family Phlebiaceae (order Polyporales), found across a broad range spanning Europe, North America, parts of Asia, and Australasia. It grows on the underside of dead hardwood logs, branches, and fallen timber in humid woodland, forming brilliant cerulean to cobalt-blue, waxy, resupinate fruiting bodies that are among the most visually striking of all wood-decay fungi. The vivid blue coloration results from the production of a pigment called corulein or is associated with the interaction of copper with fungal metabolites. Despite its startling appearance, cobalt crust is a typical white-rot fungus that decomposes cellulose and lignin in dead wood, contributing to nutrient cycling and soil formation in forest ecosystems. It is best detected during wet autumn and winter months when fruiting is most prolific. Its IUCN conservation status is Not Evaluated, consistent with its wide distribution and occurrence in many protected woodland areas. Cobalt crust is a sought-after find by mycologists and nature photographers due to its extraordinary coloration.