Asterostroma cervicolor

This is a corticioid fungus so the fruitbody forms a thin, sheet-like growth on the underside of dead wood. The surface is smooth and whiteish to very pale greyish-orange or very pale brown (like a very milky coffee). When looked at very closely the surface looks a bit like very compressed fairy floss or with some resemblance to mousse.      

The fruitbody is relatively soft, something like a compressed sponge cake, so it is easy to pick out a small piece with a needle or with very fine tweezers when you need to check the microscopic features.

This species is found in many parts of the world. It appears on dead wood in a variety of habitats.

Look-alikes

There are other whiteish to pale brownish corticioid fungi. When you see a corticioid fruiting body with the above combination of colour, surface appearance and texture, it is reasonable to assume you have a species of Asterostroma.  However, to be sure of the genus you need to put a small piece under the microscope and check that there are brown, star-like structures (called asterosetae). Then, to get to species you need to see what the spores are like.