That could be a 'reef' or an 'archipelago'.
Limestone and chalk.
from the rotting remains of tiny sea creatures that lived millions of years ago
Natural gas (and oil) is formed from the fossilized organic remains of sea creatures that were trapped in rocks at the bottom of the sea as sediments accumulated.
It can be formed in this way, or it can be formed from calcite precipitation (mineral formation from saturated solution).
Skeletal remains of many sea creatures settle on the ocean floor. Here they mix with sediments and eventually become sedimentary rock.
Limestone is formed from the skeletal remains of minute sea creatures, laid down on the sea floor millions of years ago.
I have visited one in Nicobars Island. Its made from fossils of plants/animals remains on the stones, It also has stuffed animal remains and sea creatures for display.
sea tiny animals
limestone island is for by the accumulation of dead sea creatures
It could be called an undersea island or submarisle.
Limestone and chalk.
the skeletons of tiny sea animals
all sea animals that died eventually turned into oil.
What is an ocean ridge made up of skeletal remains of tiny sea animals
yes
fossil fuel
limestone island is for by the accumulation of dead sea creatures