Where there is life there is water.
Many scientists think there is an ocean of liquid water underneath the ice of Jupiter's moon Europa.
Some even think that such an ocean could harbor some form of ocean life. Astronomers believe Neptune has an inner rocky core that is surrounded by a vast ocean of water mixed with rocky material. From the inner core, this ocean extends upward until it meets a gaseous atmosphere of hydrogen, helium, and trace amounts of methane. Comets are the icy debris of the Solar System. They are essentially large amounts of ice with some dirt in them.