Select from:
[i] it keeps an organism warm
[ii] salt and water.
[iii] granite
[iv] magnesium
[v] gastropod shells
[vi] ocean water
[vii] calcium carbonate
[viii] zinc
Q: Fact 1: Many corals secrete an exoskeleton that builds up to become a coral reef. Fact 2: Coral is calcium carbonate with a trade of carotene. Given the two facts above, a reef is made of?
A:
[vii]