I believe you mean a coral atoll
bikini atoll
the oppsite of atoll is planet
Allot and atoll.
bikini atoll
Atoll is a noun.
A atoll
The population of Namu Atoll is 801.
Ailinginae Atoll's population is 0.
Midway Atoll was created in 1988.
The population of Rongelap Atoll is 19.
Utirik Atoll's population is 409.