These two fungi may look different but they may actually be exactly the same – in theory, it should be possible to tell without resorting to a microscope. There are two possibilities: Tremella aurantia (known to the Americans as Golden ears; the British Mycological Society hasn’t assigned it a common name), which is parasitic on the fruit bodies of the Hairy curtain crust fungus (Stereum hirsutum), and Tremella mesenterica (Yellow brain), which is parasitic on the mycellium of the Peniophora species of fungi. However, those Peniophora fungi are not always easy to spot as the Tremella may have smothered the lot, so identification can still be tricky.
I’ve only knowingly seen Golden ears the once and, if you take a look at the top right corner of my image (below), you can just spot the brackets of Hairy curtain crust that helped me confirm what it was. (So, the two photos above and the very bottom photo probably all show Yellow brain but I can’t be 100% certain.)
The word Tremella means trembling, a reference to the jelly-like constituency of these fungi; aurantia means orange coloured or golden; and mesenterica joins two Ancient Greek words together: meso means middle and enteron means intestine, so maybe the title of this post should really be Golden ears and Yellow intestines. Ew!