If it's dark enough the tips glow faintly like a candle that's just been snuffed out.
You can see the glow in this blacklight photo I took (sorry if it's hard to see, I didn't turn off color correction on my phone).
The plant it's growing on is a dead piece of a Mountain Ash/Rowan shrub which seems to be bouncing back from whatever killed that branch.
Ooh, nifty! I love glowy fungi!