What am I riddles

what am Itricky

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?
The Letter A.
79.60 %
53 votes
what am I

A name of an animal minus the first three letters plus a flat piece of wood. What am I ?
(MON) KEY + board= Keyboard
79.54 %
40 votes
what am Iclever

You have me today, Tomorrow you'll have more. As your time passes, I'm not easy to store. I don't take up space, But I'm only in one place. I am what you saw, But not what you see. What am I?
Memories.
78.81 %
125 votes