A wood-rotting fungus. Fertile surface, from which the spores are released, forms a crust over the surface of the wood, a growth form called corticioid. In nature, this fertile surface usually faces downward so the spores drop out, but in the photographs, the branch has been inverted. This species is memorable because it is intensely blue, usually with a paler edge (best seen at right). When dry the surface is crusty, when moist, it is velvety smooth. The color has to be seen to be believed; and some people may refuse to believe it isn't paint. (The genus name "Pulcherricium" means "most beautiful," while "caeruleum" means "blue.")

Rarely seen, even by mushroom lovers; however, that may partly be because it hides its beauty on the underside of branches and sticks, where it remains moist for longer times.

Unmistakable, if you find it. If you search under fallen branches for it, you may find other colorful corticioids like Red and Yellow Crust (Phlebia coccineofulva), Reddish Brown Crust (Hymenochaete tabacina) and Wrinkled Crust (Phlebia radiata).