Riddles

So i was bored and i found some riddles i thought were interesting haha.

I never was, am always to be,
No one ever saw, nor ever will,
And yet I am the confidence of all
To live and breathe on this terrestrial ball.
What am I?

One more.

I am always hungry,
I must always be fed,
and the finger I lick,
will soon turn red.
What am I?

Here's one more.

The beginning of eternity
The end of time and space
The beginning of every end,
And the end of every place.
What am I?

Uno mas.

It cannot be seen, cannot be felt,
Cannot be heard, cannot be smelt.
It lies behind stars and under hills,
And empty holes it fills.
It comes first and follows after,
Ends life, kills laughter.
What am I?

haha last one i promise

This thing devours all things:
Birds, beast,trees, flowers;
Gnaws iron, bites steel;
Grinds hard stones to meal;
Slays king, ruins town,
And beats high mountain down.
What Is It?

Interesting right haha. I'll be back with the answer tomorrow I think haha.