Assertion: hardened exoskeleton | /r/MadeOf | chitin
Facets:
Source sentences:
text: The bodies of arthropods are supported by a hardened exoskeleton made of chitin, a substance produced by many non-arthropods as well.
text: The bodies of arthropods are supported, not by internal bones, but by a hardened exoskeleton made of chitin, a substance produced by many non-arthropods as well.