carpet?
Minecraft riddles

Actually, that's pretty good. It matches the entire description. Blends with plants/grass, kills by fall when you are high up in an underground ravine/ravine/over a cliff, but pay attention to this part:
"One second I am here.The next I am there." creepers don't move too fast.

nope. it vanishes and teleports. But doesn't usually knock you from really high. And it doesn't really camouflage well.

I'll add to it.
"You think i am nothing. But soon you will see. The shell will float and take you by surprise."

Clue: "The shell will float and take you by surprise."
I don't mean the shell takes them by surprise. It's the thing with the shell.

it HAS to be a mob... hmm... uh... oh! The ender dragon! Because of the annoying long thing that they expect you to read. It's like when you look at the credits when you beat the last level of a video amge and takes like 10 minutes and you can't stop it... but at least you can skip this one, because I read the full script from someone else and it would take like 1 or 15 minutes to read it at the slow rate they have it at.
Um actually its the enderman.. once he dies his secret (how he teleports) is revealed to you,
as he drops the enderpearl.
Button, i don't get it, but pressure plate is a pretty good guess. But it's not it! Keep trying! :)