Assertion: tortoise's scale | /r/MadeOf | keratin
Facets:
value: as human fingernails
type: OTHER
Source sentences:
text: The shell is covered with scutes, scales that are made of keratin (the same protein that our fingernails are made of and the horn of a rhino).
text: The scales on the outer shell of a tortoise are made of the same keratin as human fingernails.