A colorful creature, lit up like a children's toy with its tentacles extended in all directions like sunrays, has been spotted swimming the world's deepest ocean trench.

Scientists discovered the hydromedusa jellyfish on April 24, the National Oceanic and Atmospheric Administration (NOAA) reports. It likely belongs to the genus Crossota, a classification of jellyfish that spend their entire lives gliding through the water, bypassing others' stationary phase.

The ethereal creature was captured on video as it swam about 2 miles below the surface of the sea by "Okeanos Explorer," a NOAA ship that discharges remotely operated vehicles into deep waters, and uses a hull-mounted, multibeam sonar to explore and map the sea floor.

The newly discovered jellyfish has two sets of tentacles, short and long. When the the long tentacles are even and extended outward, and the bell is motionless, this could mean it's readying to ambush its prey, scientists speculate. Inside the bell, red radial canals connect what scientists say looks like the bright yellow gonads.

This discovery of a totally new jellyfish underscores just how much is left to learn about the ocean, a big part of the reason the Okeanos crew is on a three-year mission to explore US marine protected areas in the central and western Pacific.

From April 20 to July 10 the crew will study the geology and look for new deep-sea life in the waters surrounding the Mariana Archipelago east of the Philippines. There lies the Marianas Trench, a 1,500-mile long and 43-mile wide trough in the ocean floor, with its deepest point 7 miles below the surface of the ocean.

"If Mount Everest were dropped into the Mariana Trench, its peak would still be more than a mile underwater," as National Geographic points out.

Most of the area is a US protected zone that's part of the Marianas Trench Marine National Monument, established by President George W. Bush in 2009. It includes about 155,000 square miles of submerged lands and waters, says NOAA, which is working to better understand the deep sea in order to better manage and protect it.

An area of ocean near the archipelago and national monument has the highest concentration of valuable deep-sea minerals, which are sought after by Russia, Japan and China. But mining the Earth's crust here could have "potentially severe ecological consequences," says NOAA.

"The deep seafloor of the Pacific Ocean is one of the most poorly explored regions on Earth with very little known about the benthic (at the bottom of the ocean floor) animals that live beyond 3,000 feet in the PCZ (Prime Crust Zone)," according to NOAA.

Even though the ocean covers more than 70 percent of the planet's surface and supports all living organisms, 95 percent of it is unexplored by humans. In fact, we know more about the surface of Mars than about the depths of our own planet.

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In December 2015, the X Prize Foundation, which promotes technological innovation, launched a three-year challenge to encourage scientists to produce robots that will map the seafloor and be able to detect life in deepest reaches of the sea.

These technologies could revolutionize deep-sea exploration, which has been limited, the X Prize explains, by the high cost and extreme physical challenges associated with the deep ocean, where explorers would have to contend with frigid temperatures, no light whatsoever, and water pressure "the equivalent of one person trying to support 50 jumbo jets," according to NOAA.