Lots of people got it right. I'll be leniant this time on those who didn't include their ingame name the first time or put the proper PM title "Riddle", but next time those who don't your win doesn't count!
The answer was: Coal
Winners:
Alexander / Alexander (first correct answer)
Culex / Cucu
ZeroEdge / ZeroEdge
silvanel / silvanel
Kadar / Kadar
Nimitz / PeekaBoo
Myuuu / Myuuu
SwiftStrike / Swift
Lis and Olo / Salvosa
Lucky Day / Lucky Day
Sir Aun / Sir Aun
Rei Ayanami / ?
Yamaha / Yamaha
That's 13 winners, I admit this one was kinda easy, but it's nice to get back into the riddle event smoothly
The other most common answers I got was a matchstick, nice answer, but unfortunatly not the one I was looking for. And.. pencil? wth..