I'm in a zoo,
But not in a jungle.
I rarely come in pairs,
But I'm in every puzzle.
Some think I'm in a xylophone,
But I most certainly am not.
You don't see me with a loan,
But very strangely in a zealot.
I'm in the magical prison of Azkaban,
Well, can't you see?
I'm in the buzz of a fan,
But, my oh my what could I be?