An exoskeleton is a thickened, rigid cuticle which is stiffened by mineralization, as in crustaceans or by the cross-linking of its proteins as in insects.
ɐn ˈɛksoʊskˌɛlᵻtən ɪz ɐ θˈɪkənd, ɹˈɪdʒɪd kjˈuːɾɪkəl wˌɪtʃ ɪz stˈɪfənd baɪ mˌɪnɚɹəlᵻzˈeɪʃən, æz ɪn kɹʌstˈeɪʃənz ɔːɹ baɪ ðə kɹˈɔslˈɪŋkɪŋ ʌv ɪts pɹˈoʊtiːnz æz ɪn ˈɪnsɛkts.