Animals:
* Hair: The primary component of hair in mammals.
* Nails/Claws/Hooves: Provide protection and support.
* Skin (outer layer): Keratinocytes produce keratin, which forms a protective barrier.
* Feathers: The main building block of feathers in birds.
* Horns: The outer sheath of horns in animals like cattle and sheep.
* Beaks: Found in birds and some other animals.
* Scales: In reptiles and some fish.
* Quills: In animals like porcupines.
* Calluses and corns: Thickened skin areas formed in response to pressure or friction.
Products and uses of keratin:
* Cosmetics: Used in hair care products (shampoos, conditioners, styling products) to strengthen and smooth hair.
* Pharmaceuticals: Keratin-based materials are being explored for drug delivery systems and wound healing applications.
* Textiles: Keratin fibers can be processed into fabrics.
* Agriculture: Keratin waste (e.g., feathers) can be processed into fertilizer.
* Bioplastics: Keratin is being researched as a component for biodegradable plastics.
Essentially, if it's a tough, protective, and fibrous structure on an animal (or derived from an animal), chances are it's largely made of keratin.