The correct answer is 2) coral polyp. Coral polyps are cnidarians that secrete calcium carbonate to form a hard skeleton, creating coral reefs. Oysters, while having a hard shell, are mollusks, not cnidarians. Jellyfish and anemones do not build hard skeletons.
a cnidarian that builds a hard calcium skeleton around itself?
1)oyster
2)coral polyp
3)jellyfish
4)anemone
1 answer