Yellow Slime Mould

A yellow slime mould, possibly Badhamia utricularis (based on comparison with photos here, here and here). 

At this stage of its life cycle, the slime mould is in effect a single giant multinucleate cell called a plasmodium.  In this form it spreads out to feed and, later on, it moves off to a drier location where it develops fruiting bodies and releases spores.

The slime mould in these pictures seemed to be attacted to the orange fungus that was growing on the same decaying log.

Photos taken in Whiteknights Park, Reading University grounds, Reading, UK, on 2010-01-23.