Hard to find a scale to work with.
It looks like it might be a fungus of some sort.
Equally, it looks like it could be a nest for a moth or catterpillar.
How's that for an unhelpful answer?
:)

looks like shaving foam! I only know of one mushroom that looks like that and that is a puffball, but i am unsure as to whether or not they grow on dead trees. I think i would go with the suggestion of nest.

I think someone's been spreading meringue on the stump! Are you sure its genuine?

looks like a cotton wool ball. could one have been dropped?

I think it's a type of slime mould. One of these was used in an old sci-fi film called The Blob from Outer Space! Hope yours doesn't stage a world take over bid! Google slime moulds, very interesting, I thought.

i have seen one of them 1 meter off the base of the tree sticking on like chewinggum...slime mould, fungi it could be one of them,but they both grow on trees and both do the same job(1decomposing dead plant and animal material or2 just being a parisite,taking food off its host tree!! and i think 2 is the case!) in the end they turn brown as i saw the next day visiting this mysterios blob i think its dead now :(
happy to help!