Life as We Don't Know It

The prawn-like creatures in summer blockbuster "District 9" develop an unhealthy addiction to cat food. This is simultaneously disgusting and hilarious to us, but the question of how hypothetical aliens might sustain themselves is incredibly open-ended. Researchers at the University of Vienna are looking into the possibility of life forms that sustain themselves on sources of energy uncontainable to humans:

One requirement for a life-supporting solvent is that it remains liquid over a large temperature range. Water is liquid between 0°C and 100°C, but other solvents exist which are liquid over more than 200 °C. Such a solvent would allow an ocean on a planet closer to the central star. The reverse scenario is also possible. A liquid ocean of ammonia could exist much further from a star. Furthermore, sulphuric acid can be found within the cloud layers of Venus and we now know that lakes of methane/ethane cover parts of the surface of the Saturnian satellite Titan.

Water is one of the foremost prerequisites for intelligent life, and astronomers have narrowed their search for aliens accordingly. If a planet isn't just the right distance from its star, then it won't have water, and it won't have aliens. When you take the whole water thing out of the equation, the possibilities increase exponentially.

If such life forms do exist, I picture street peddlers selling bottled sulphuric acid to gridlocked motorists next to the highway. They have evolved to sustain themselves on a charcoal-rich diet, and as a result, their skin is notably dry and damaged. We could sell them our Neutrogena, but it would probably be like acid to them and they'd likely misinterpret our dermatological altruism.