Billions of years ago, Earth may have been shrouded in a blanket of atmospheric haze like that seen on Saturn's moon Titan, providing organic material that nourished our planet's earliest life forms, researchers said on Monday. Some scientists look to Titan as a model for what early Earth's atmosphere may have looked like. They think Titan's atmosphere, packed with organic aerosol particles created when sunlight reacts with methane gas, may offer clues about Earth's climate when primitive organisms were first arising 3.6 billion years ago.