That's my Clack, and it's Gummyrot Skull directly from Elitekeybords.com, it's a real one, a Gummyrot green translucent key, on my Poker2 Blue LED light…
It has a rectangular FXE Stamp on the back of it. I am making a video of the key on board, with LED on then switching on and of and different level of brightness of the LED,
and then taking it off and showing the back of the key of it… but my camera focus poorly…… you can see clearly there is marking on the back of the key,
just difficult to recognize the full characters.
Will post the link of the video, if anyone are interested, may see the video, it's around 100mb, gonna take sometime with our local broadband service.