The Good Life - Is this mushroom a Gyromitra Esculenta or false morel? No, but it could be Hellvella Palustris!

Side view of the mystery mushroom

We went on a wander through the woods this evening and Corinne found this mushroom growing alone on mossy ground. The cap has billowing folds but is not folded and creased like a brain typical of a false morel. The outside of the cap was a light grey in colour. We cut the mushroom in half to check out the interior and it was indeed hollow and light coloured. The small foot, white in colour, was not quite hollow but had chambers.

The closest type of mushroom I can relate it to is the gyromitra esculenta but it has obvious differences. Anybody got any ideas?

Cross section of the mystery mushroom (on a similarly coloured rock) with the foot on extreme left and right

After much thought, deliberation and reviewing a few French publications I am of the opinion this is HELLVELLA PALUSTRIS - 2nd September 2009