Answer:
Die without me, never thank me. Walk right through me, never feel me. Always watching, never speaking. Always lurking, never seen.
What word has kst in the middle, in the beginning, and at the end?
When liquid splashes me, none seeps through. When I am moved a lot, liquid I spew. When I am hit, color I change. And color, I come in quite a range. What I cover is very complex, and I am very easy to flex.
I am the fountain from which no one can drink. For many I am considered a necessary link. Like gold to all I am sought for, but my continued death brings wealth for all to want more.
According to the music industry, you can count on a midnight train and the devil to turn up here.
I repeat only the last word you say. The more I repeat, the softer I got. I cannot be seen but can be heard. What am I?