Context: A 500-metre-tall coral reef discovered by Australian scientists, off Australia's Great Barrier Reef.
It was the first detached reef of that size to be discovered in over 120 years and that it was thriving with a “blizzard of fish” in a healthy ecosystem
It lies 40 metres below the ocean surface and about six kilometres from the edge of Great Barrier Reef.
The discovery comes after a study earlier this month found the Great Barrier Reef had lost more than half its coral in the last three decades.
Using the underwater robot known as SuBastian, the scientists filmed their exploration of the new reef.
Great Barrier Reef
The Great Barrier Reef runs 2,300 km down Australia's northeast coast spanning an area half the size of Texas.
It was world heritage listed in 1981 by UNESCO as the most extensive and spectacular coral reef ecosystem on the planet.
Coral reef:
A coral reef is an underwater ecosystem characterized by reef-building corals.
Reefs are formed of colonies of coral polyps held together by calcium carbonate.
Most coral reefs are built from stony corals, whose polyps cluster in groups.
“Main types" of coral reef are the fringing reef, barrier reef, atoll, "bank or platform reef" and patch reef.
Coral reefs deliver ecosystem services to tourism, fisheries and coastline protection.