Ganymede also has a thin oxygen atmosphere and is believed to have a saltwater ocean 200 km below the surface. This ocean would have more water than all of the water on Earth's surface.

Ganymede is the only known moon that has a magnetic field, and that is why it has been colonized, beltalowda

Mercury is actually twice as massive though as it is much more dense than Ganymede. Its core makes up 42% of its volume.

Nobody is as dense as the Earth though. We are fucking dense.