Good read here: https://en.m.wikipedia.org/wiki/Chitin

I will say I spoke too soon. I thought marine Arthropoda had exoskeletons made of calcite but it is chitin. Calcite leads to limestone which is very sensative to PH. Chitin apparently is different and is much more complex so perhaps there is room for adaptations there.
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Maybe he's born with it.

Maybe it's amphetamines.