Dead Man's Fingers - Xylaria polymorpha

The blackish fruitbodies are variable in shape, but are usually thick, squat and rounded at the tip, occasionally branched or lobed. Initially they are covered in greyish conidia, the asexual stage.  In the sexual stage, spore-producing perithecia develop in the white stroma inside the fruit body.  The perithecia are seen as tiny pimples on the outer surface.  Eventuially the spores are ejected through minute ostioles. 

Dead Moll's Fingers (Xylaria longipes) is usually longer and more slender, with a tapering tip and stem, and is almost exlusively on Sycamore, Both species are variable in form and some specimens may need to be examined microscopically to identfy with certainty.. Sometimes confused with Earth-tongues (Geoglossum) but these grow in grasslands, not on dead wood

Photograph in habitat; note substrate and associated tree species.  

On decaying deciduous wood