Coral is the word you are looking for.
atoll
You cannot use the "word" coral reef in a sentence, but you can use the "words" coral and reef adjacent to each other in a sentence.
The German word for coral reef is (das) Korallenriff
The coral reef is protected by law.Be careful you don't crash the boat into the reef.
The coral reef is a very important resource
lagoon maybe?
This appears to be a typo of the word "coral" (marine reef-building animals).
The collective noun for coral is a reef of coral or a bed of coral.Although the plural form, corals, is the correct form for the living creatures themselves, the part that of the coral that is seen, the reef or the substance from which things are made, is an uncountable noun, a word for a substance. There is no collective noun for the live creatures.
The Great Barrier Reef.
Coral can represent many things such as life or death depending on how you look at it, because of its makeup (many different dead organisms that create something new) It can represent reefs which consist mostly of coral.
The collective noun for coral is a reef of coral or a bed of coral.Although the plural form, corals, is the correct form for the living creatures themselves, the part that of the coral that is seen, the reef or the substance from which things are made, is an uncountable noun, a word for a substance. There is no collective noun for the live creatures.