This is the filament inside an old fashioned light bulb.
The bulb hangs in one of our outbuildings, from a slightly dodgy looking bit of green wire. We don’t go in there very often, so we haven’t got round to swapping it for a new low energy bulb.
I guess it will die eventually, and we’ll have to make the change. I don’t think you can even buy this sort of bulb any longer. In the mean time, it shines bravely on.