HAPPY HALLOWEEN!
In a deep dark forest, fallen and rotting logs litter the damp forest floor. Everything is still and silent. No birds sing; no deer trot across the path. The only sound is a weak wind that rustles high in the leaves. The branches are so dense that you can’t catch a glimpse of the sky; the only patch of color is a brilliant autumn leaf that has fallen on a nearby log. But wait! What is that? It’s no leaf. It glistens. It jiggles. It looks like a tiny orange brain clinging to the decaying wood.
This is witch’s butter, or Tremella aurantia. It’s a parasitic fungus–but it’s actually not feeding on the wood of the log, but on another fungus (Stereum hirsutum, or false turkey tail) which in turn is feeding on the dead tan oak. The legend behind the name is that witch’s butter will grow on your gate if a witch has put a hex on you… in order to break the hex, you have to kill the fungus by poking it with pins. It is described as edible but without flavor–the kind of thing a tasteless witch might eat?
There are a few other kinds of witch’s butter that also grow in the area. The best way to tell them apart is by host and where they grow. The one featured here is found on hardwoods (like tanoak), and feeds on false turkey tails–so you’ll see some of these little fan-shaped fungi nearby on the log. It’s cousin, Tremella mesenterica, also grows on hardwoods but feeds on a spreading mold-like fungus called Peniphora. The third (Dacrymyces palmatus) grows only on wood of conifers.
Usually I’ve seen witch’s butter growing in moist forests; the one described above is a stretch of the International trail, and birds actually sing there quite often… Though you can find a silent moment if you try. 
Flowers Of Marin 