Neptune has a moon known as Triton and this can perhaps be one among the most captivating worlds in the solar system. This bizarre moon has several unique features, three of which are its volcanic activity, and odd rotation pattern, clockwise, in contrast to the majority of large moons.

But it is not only external and the manner it orbits that provoke interest, it is the outer icy crust and the possibility to have an ocean under the crust containing all required to support life.