Scientists plumbing the depths of the Mariana Trench -- the deepest part of the ocean on the planet -- have identified gigantic amoebas lurking miles and miles beneath the waters.

The creatures are called xenophyophores, and scientists from the Scripps Institute of Oceanography at UC San Diego spotted them in the cold, crushing depths 6.6 miles beneath the white caps.

"They are fascinating giants that are highly adapted to extreme conditions but at the same time are very fragile and poorly studied,” said Lisa Levin, a deep-sea biologist and director of the Scripps Center for Marine Biodiversity and Conservation.

Scripps scientists said xenophyophores are among the largest individual cells in existence, often growing longer than four inches. Recent studies indicate that by trapping particles from the water, xenophyophores can concentrate high levels of lead, uranium and mercury and are thus likely highly resistant to large doses of heavy metals. They also are well suited to a life of darkness, low temperature and high pressure in the deep sea.

“The identification of these gigantic cells in one of the deepest marine environments on the planet opens up a whole new habitat for further study of biodiversity … and extreme environment adaptation,” Levin said.

To reach the bottom of the ocean requires special equipment. Levin worked with Eric Berkenpas and Graham Wilhelm -- Remote Imaging engineers from the National Geographic Society -- to build and launch “dropcams."

“Dropcams are versatile autonomous underwater cameras containing an HD camera and lighting inside of a glass bubble,” Berkenpas explained.

By wrapping high-resolution cameras in a thick-walled glass sphere, scientists were able to drop cameras capable of withstanding the extreme pressure of all that ocean. At a depth of 6.6 miles, the water above can cause more than eight tons per square inch of pressure.

Life is surprisingly abundant at these extreme depths, despite the cold and pressure. According to Dhugal Lindsay of the Japan Agency for Marine-Earth Science and Technology, the Dropcam movie also depicts the deepest jellyfish observed to date.