An extremely rare giant Phantom Jellyfish was spotted at California's Monterey Bay, and marine scientists at Monterey Bay Aquarium Research Institute (MBARI) have recorded footage of the unusual sighting.

The stunning video of the massive jellyfish with long oral arms and a gigantic bell-shaped body, undulating the deep waters has fascinated social media. The video shared on MBARI's Facebook page and Youtube last week has fetched more than 590,000 views since then.

Characterized as one of the most elusive sea creatures, Phantom Jellyfish, also known by their scientific name Stygiomedusa gigantea was spotted by MBARI’s remotely operated vehicle (ROV) Doc Ricketts around 90 meters (3,200 feet) deep below the sea. Though MBARI has made thousands of expeditions before, phantom Jellys were only spotted nine times to date, according to a report by MBARI.

After a closer look at the phantom jelly with the help of submersible lights, the scientists at MBARI said the bell of the sea animal measured more than one meter across. The four ribbon-like arms of the jelly act as its mouths and they could grow more than 10 meters in length.

Scientists also found an eel-like fish that belonged to pelagic brotula species (Thalassobathia pelagica) swimming alongside the phantom jelly. The massive jelly acted as a cover, allowing smaller fish to hide from larger predators, Gizmodo reported.

When the fascinated viewers asked about the actual color of the phantom jelly, the research group replied on the page: "Like many deep-sea animals, the giant phantom jelly (Stygiomedusa gigantea) has a reddish coloration. Red light cannot penetrate the ocean’s depths, so animals that are red appear black and camouflaged in the darkness. Scientists do not know which animals might prey on the giant phantom jelly, but its crimson color and large size likely help deter most predators."

Though the first specimen of phantom jelly was collected in 1899, very little is still known about the species to date. Phantom jellyfish was officially recognized as a species 60 years after the first sighting. They are found worldwide, except for the Arctic Ocean, and mostly feed on small fish and plankton.

The sheer size of some jellyfish can be a threat to fishermen if they caught in their nets
The sheer size of some jellyfish can be a threat to fishermen if they caught in their nets YOMIURI SHIMBUN FILES / YOMIURI SHIMBUN