Are you ready for a challenge?

Here is a set of pictures I have taken over a period of over eight days, from 26th April to 3rd May 2010. I found this strange thing on a dead alder close to the river bank, and full of old woodpecker holes.

The change from a soft papery covered mass to a woody lump, to a spongy spore case was astonishing. Does anyone have any idea what  this is? Its papery, softish and with lumpy bits inside, about two  inches across and no definite entrance hole. I suspect the woodlouse was just passing.

Over the eight days it got fuller and harder and eventually the surface was peeling to reveal a hard cocoa powder like mass. It  became like an expensive home-made chocolate, the white cover was all gone.

I happened to bump into Alan Willmot on the Reserve, and he identified it as a .......................  

Click on the smiley to get the answer