Coral reefs are accumulated from the calcareous exoskeletons of marine invertebrates of the order Scleractinia (stony corals).
kˈɔːɹəl ɹˈiːfs ɑːɹ ɐkjˈuːmjʊlˌeɪɾᵻd fɹʌmðə kˈælkɛɹəs ˈɛksoʊskˌɛlᵻtənz ʌv mɚɹˈiːn ɪnvˈɜːɾɪbɹˌeɪts ʌvðɪ ˈɔːɹdɚ sklˌɛɹɐktˈɪniə stˈoʊni kˈɔːɹəlz.