The beak of the birds varies in sizes and shape. Its purpose is for feeding. The shape accords to what the bird eats. Here are some of the terms you can describe a bird's beak:
* cone shaped bill
* pointed beaks
* strong beaks
* long beaks
* sharp beaks
* thin beaks
* slender beaks
* tubular beaks
* hooked beaks
i think the answer is
a substance that is naturally found in the brain