Assertion: arachnid's exoskeleton | /r/MadeOf | chitin
Facets:
Source sentences:
text: Scorpions have an exoskeleton (external skeleton) made of chitin, a tough, protective, flexible molecule made of polysaccharide and nitrogen.
text: The exoskeleton of a chelicerate is a hard external structure made of chitin that protects the arthropod, prevents desiccation, and provides structural support.