With thieves I consort,
with the vilest, in short,
I'm quite at ease in depravity;
Yes all divines use me,
And savants can't lose me,
For I am the center of gravity.
While I am in air, I am not in oxygen.
I am also in water, but not in hydrogen.
I am necessary in all animals, but you won't find me in the zoo.
Look in all brains and you'll find me there too.
What am I?
Alone I am 24th, with a friend I am 20.
Another friend and I am unclean.
What am I?
The letter 'X'. It is the 24th letter of the alphabet, XX in Roman numerals is 20, and XXX is a label for movies that are very inappropriate (unclean).
