Assertion: blue whale's baleen | /r/MadeOf | keratin
Facets:
Source sentences:
text: Baleen are plates made of keratin – the same material that your hair and fingernails are made of.
text: Baleen are plates made of keratin – the same material that your hair and fingernails are made of.
text: Baleen looks like long, tightly-packed brush bristles, and is made of keratin, which is the same substance that makes up your hair and fingernails.