Kiritimati or Christmas Island
These atolls are both in the Marshall Islands.
No, the word atolls is the plural form for the singular noun atoll. Example:There are a number of atolls on the coast near my home.
Atolls are formed first as a reef that fringes a volcanic island. The two largest atolls are Suvadiva in the Maldives Island and Kwajalein in the Marshall Islands.
Just the one island.
On an island
crustal sinking
crustal sinking
Atolls
Bryan (1953) lists about 400 atolls. The full article is available through http://www.botany.hawaii.edu/faculty/duffy/arb/019-23/v019-23.pdf. This is not a definitive list as the definition of an atoll is still the subject of discussion discussion. Bryan, E.H., 1953. Check list of atolls. Atoll Res. Bull., 19: 1-38.
Atolls don't float to start with. There is land, the remnants of former volcanic islands, beneath them. The lagoon in the centre is not connected to the sea.
Tuvalu consists of nine islands, six of which are atolls and three of which are coral reefs.