But even after decades of research, marine biologists have not been able to figure out how the small amount of nutrition in marine snow can support the large numbers of organisms that live on and in seafloor sediment.

MBARI researchers have been working on Benthic Rover since 2005, overcoming many challenges along the way.

The most obvious challenge was designing the rover to survive at depths where the pressure of seawater is about three tonnes per square inch. To withstand this pressure, the engineers had to shield the robot's electronics and batteries inside custom-made titanium pressure spheres.

To keep it from sinking into the soft seafloor mud, the engineers outfitted the vehicle with large yellow blocks of buoyant foam that will not collapse under extreme pressure, said an MBARI release.

This foam gives the rover, which weighs about 1,400 kg on land, a weight of only about 45 kg in seawater.