Tulasnella sp.

A Tulasnella fruit body is often little more than a wash of colour on the underside of some piece of wood (e.g. a fallen branch, a bark slab lying on the ground, etc). Common colours are grey, lilac or pink (or some mix thereof) and in a number of species the colours are quite faint, making the fruit body almost invisible macroscopically. Sometimes it is necessary to at tilt the piece of wood, so as to catch the reflected light at various angles in order to be sure that there is something on the wood's surface. Whenever I see a faint wash of colour (in particular a faint pastel lilac or pink) I guess Tulasnella, but confirmation requires a microscopic examination. On drying the fruit body colour may fade and herbarium specimens (even of those species visible to the naked eye when fresh) may become virtually invisible.    

A technical note: Tulasnella is a basidiomycete genus. The basidium is not septate and the sterigmata start as globular outgrowths. In general, a mature sterigma has a narrow base above which it is swollen but then tapers to a sharp apex. A mature sterigma is cut off from the basidium by a cross wall, the basidium may shrivel and it is common to see the four sterigmata, well inflated, still attached to the shrivelled basidium. These features make it easy to identify the genus microscopically.

(Ref: ANBG )