Errr... that was a LONG time ago
Basically, I made a 0.5mm pencil lead glow white hot by connecting it across a DC power supply (not easy to do without it breaking first... I only got that ONE picture), then asked people on HWZ forums whether they could guess what it was
Turned out that ckiang was the one who guessed correctly.
By the way, here's the pic if anyone's interested.
Do not try this yourself! I was quite lucky I didn't set fire to the contents of the bin...