Cobalt Crust - Terana coerulea

Alternative names
Pulcherricium caeruleum

This corticioid (crust-like) fungus is a real beauty, especially when young and fresh with a bright cobalt blue appearance. The rounded fruit-bodies coalesce to form irregular large patches with either smooth or slightly bumpy or warty fertile surfaces that are usually finely velvety. This is a very thin crust fungus, generally much less than 1 mm thick. When moist, the texture of these crust fungi is quite soft with a waxy feel, and the outer margins are pale, sometimes whitish, and finely fringed. Old specimens turn dark blue and eventually almost black.

Identification difficulty

Found on dead hardwood trees and fallen branches, particularly Ash (Fraxinus excelsior).

When to see it

All year round.

Life History


UK Status

Infrequent or occasional in England and Wales and very rarely recorded in Scotland and Ireland.

VC55 Status

Infrequent in Leicestershire and Rutland. The Barnsdale record of January 2017 is the 6th record for VC55.

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Leicestershire & Rutland Map


Yellow squares = NBN records (all known data)
Coloured circles = NatureSpot records: 2020+ | 2015-2019 | pre-2015

UK Map