On the flat ice of Europa, the second of Jupiter's four major satellites and may be the smoothest globe in the solar system, Brinker-roos might frolic, on feet shaped like skates. They lead a carefree life, living on pure energy as they zoom across the endless frozen plains. Since there's no air to breath, and no food to eat, Brinker-roos need no mouths or noses. Instead, their green skin performs photosynthesis, as plants do. And the coils on their backs pick up energy from Jupiter's strong magnetic field, which Europa must travel through as it orbit's Jupiter.