One would think the Wikipedia article on mantis shrimp would have that sort of information, but it doesn’t.
Apparently it uses chitin in a spring mechanism, according to this: [https://www.reed.edu/biology/courses/BIO342/2012_syllabus/2012_WEBSITES/HW%20mantis%20shrimp/Mechanism.html](https://www.reed.edu/biology/courses/BIO342/2012_syllabus/2012_WEBSITES/HW%20mantis%20shrimp/Mechanism.html)
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