Crumpet?

Phlebia tremellosa (Jelly Rot) - underside.  Knole Park, 3 November 2012

How can something grow into an intricate pattern like this, weaving over and under alternate ribs?  This is the underside of a fungus from a fallen treetrunk.  It had a soft texture and reminded me of an uncooked crumpet.  The upper side was also creamy white, but hairy rather than patterned.

Phlebia tremellosa (Jelly Rot) - upper side.  Knole Park, 3 November 2012