...and the real story here is that the difference between 'squish' and 'crunch' is that, in crunchy (hard) cuticle, the protein/chitin/pigment composite material is more strongly crosslinked than in squishy (soft) cuticle.
The real takeaway here - the new part of this news - is that the crucial difference is the degree of crosslinking in the cuticle material.
So the answer is "crosslinking (in cuticle)", not just "cuticle." [smiley goes here*].
* "smiley," I say, not "idiotic-looking yellow cartoon face."
Bah. Fookin' b&d software.