Assertion: toucan's bill | /r/MadeOf | keratin
Facets:
Source sentences:
text: Instead, their bill is made of keratin (yes the same stuff our finger nails are made of) which makes it very light.
text: As mentioned, the bill is made of keratin – what else is made of keratin?
text: The bill is made of keratin, a very lightweight material so it is easy to move about with it, but it's not very strong so it is not considered good protection against predators.
text: In terms of surface area used for this function, the bill relative to the bird's size is amongst the largest of any animal and has a network of superficial blood vessels supporting the thin horny sheath on the bill made of keratin called the rhamphotheca.