Assertion: hedgehog's spine | /r/MadeOf | keratin protein
Facets:
value: with a muscle for each spine
type: OTHER
value: with a hollow shaft
type: OTHER
Source sentences:
text: A Southern African hedgehog is covered with spines all over its body except for its face, belly and ears, and these spines are made of keratin protein with a hollow shaft and a muscle for each spine.