"green stain fungus" (chlorociboria aeruginascens)

...of particular interest is that the mycelium - the part of the fungus that grows in the substrate and forms the bulk of its mass - stains the substrate (wood) a green or bluish green colour. this is done via the production and deposit of xylindein, a naphthoquinone. the green-stained wood was and is used by woodworking artists, occurring at least as early as 14th century italy in instarsia panels.

(from the ubc botanical garden's botany picture of the day.)

thanks jess!!!