Assertion: blue whale's plate | /r/MadeOf | keratin
Facets:
Source sentences:
text: Instead, they have a system of fringed plates made of keratin (fingernail-like material) that filter out prey rather than tearing it apart.
text: Instead of teeth, humpbacks and other baleen whales use fibrous plates made of keratin to strain their food.
text: The classification refers to the baleen plates, made of keratin, on both sides of their upper jaw.