Assertion: blue whale's baleen plate | /r/MadeOf | keratin
Facets:
Source sentences:
text: Adult baleen whales do not have teeth, but instead, they possess baleen plates which are made of keratin.
text: There is a large strong bony projection from the front of the "brain case" called the rostrum, from which baleen plates (made of keratin, like skin, fingernails, hair, hooves and rhino horns) hang on either side.