The creatures, known as xenophyphores, also host a range of other, multicelled organisms.
Samples of trench communities have turned up a range of more complex creatures, including shrimp, fish, and soft-shelled snails uniquely adapted to their harsh home.
The sea floor Cameron saw, however, was barren, he told reporters. He said never reached a place that looked to host any interesting biology.
For the creatures that do live in the deep, researchers are trying to figure out where they get their food, as well as the pecking order in the food chain at such depths.
The region also is of interest to astrobiologists as they explore approaches to detecting and studying life on other planets or moons. Jupiter's moon Europa and Saturn's moon Enceladus are thought to have small oceans under their icy crusts. Any future mission to explore those oceans would require some kind of sensor package sent into the depths.
And there's plenty of ocean exploration to do on Earth, notes Bob Gagosian, president of the Consortium for Ocean Leadership, a nonprofit organization in Washington that focuses on building support for ocean research and ocean policy.
Despite some 200 years of oceanography, scientists have explored a scant 5 percent of the planet's oceans, he says. For him, Cameron's dive is significant for the spotlight the filmmaker's efforts are throwing on ocean exploration and for the technology the Deepsea Challenger exhibits – in particular the stunning speed of descent and ascent.