bikini atoll
a group of small coral islands in the shape of a ring that encloses a lagoon
the oppsite of atoll is planet
An atoll is formed first as a reef that fringes a volcanic island. As the island sinks (after the volcanic activity has ceased and the crust has cooled, becoming denser), the reef continues to build upward, eventually ending up as a ring-shaped structure.
Atoll is a noun.
bikini atoll
Allot and atoll.
A tropical lagoon is encircled by an atoll.
The Bikini Atoll is an atoll in the Marshall Islands and was the site of many American nuclear tests in the 1940s and 1950s.
A atoll
Let's not strand ourselves on this atoll.
Aur Atoll's population is 438.
Lae Atoll's population is 319.