Scientists dove down to 800-meter-deep waters in the Coral Sea off northeastern Australia - and found astonishing species, some of which had never been observed before. Have a look at what is living in the depths.
No human being has ever been there, at a depth of 800 meters (2,600 feet) at Osprey Reef, northeast of Queensland.
German and Australian scientists sent an unoccupied, remotely operated submarine there, to capture photos, videos and even live samples of the versatile life lurking in the depths.
"At 800 meters depth, the water is cold, with no light ever reaching this depth. Until this expedition few people knew what was down there," Robin Beaman of James Cook University in Cairns, one of the involved scientists, told the dpae wire service.
They discovered unique sponge gardens, with two species of glass sponges never seen before.
These animals' skeletons are made of silica, instead out of carbonate, like other sponge species.
"If you look at them through a microscope, you can see little glass spicules [spikes] in living flesh," Beaman said.
About 600 species of glass sponges exist. Sponges are believed to be able to live for up to 15,000 years.
Large colonies of shimmering golden corals and precious red coral, used in jewelry-making, were also found. Such varieties were not known to live in the Australian waters, Beaman said.
Glass sponges and corals are animals, even though they you wouldn't guess that just by looking at them.
The same is true for sea lilies and feather stars, also discovered at Osprey Reef.
They both belong to the family of crinoids. They can live in shallow waters, or in depths of up to 6,000 meters.
Sea lilies are attached to the sea floor by a stalk.
Feather stars, though, can move around on the sea floor. They often hide in crevices during the day, and come out in large numbers at night for feeding.
A scuba diver's paradise
Osprey Reef's lies 125 kilometers (78 miles) north east off the famous Great Barrier Reef in a marine reserve.
Here, almost vertical reef walls rise from the 1500- to 2500-meter deep bottom of the ocean.
Its lagoon with a depth of 30 meters (98 feet) is very popular with scubadivers.
The reef is home of the smallest fish know, the stout infantfish, only up to 8 millimeters (0.33 inches) long.
It also harbours a dwarf form of the chambered nautilus, a scavenger cephalopod that has about 90 tentacles with no suckers.
Scientists conducted their so-called Deep Down Under expedition in 2009.
The analysis of the findings was published this month in Marine Biodiversity Journal.