Titan is the second largest moon in the solar system and is one of only 3 world in the solar system known to carry indigenous life. Unlike Earth and Europa Titan has no complex multicellular organisms though its life forms are very exotic. Titan's life consists of bacteria-like organism that thrive in methane lakes that exists on Titan surface, viruses that are very similar to Europa's (possibly from Europa?), and large single celled fungi-like organisms that can be up to half a milimeter in size which thrive in methane lakes and deep below the surface. Unlike Europa, Titan has widespread colonization throughout its surface with a human settlement population of around 300 million.