Answer: Chitin

You might know it only as that crunchy stuff you feel when you squash a wayward bug in your house, but the crunchy stuff has a technical name: chitin. The exoskeletons of insects are made up of the stuff—a long-chain polymer derived from a glucose derivative.

In its pure form, it is translucent, pliable, resilient, and quite tough, but is widely and wildly modified giving us everything from the thick and dark shells of beetles to the razor thin and iridescent wings of butterflies.

Chitin isn’t just found among insects either, but makes a wide range of appearances in nature including the exoskeletons of arthropods (crabs, lobsters, and shrimp), the beaks of cephalopods (squid and octopuses), the scales of fish, and the cell walls of fungi just to name a few.

The oldest preserved sample of chitin is around 25 million years old and consists of a scorpion preserved in amber.