crusts or slime moulds?

[animartco]

I have found that crust fungi look very similar to large masses of slime mould which also form crusts. Is there an easy way of telling them apart?
I have a strange white 'crust' in a hollow in an old apple tree in the garden which is still soft after a couple of months. I have been trying to get pictures of it up here but with no luck.

[mollisia]

Hello,

if it is still there after several month, it can be no slime mould. Those slime moulds have a life cycle of only a few days or may be two weeks.

best regards,
Andreas