Moons are a type of planet made up of Moondust, Moon Rock, and Moonstone. They are always Harmless in terms of threat level, and are great sources of fuel, as Erchius Crystal Fuel can be found of the surface, and Liquid Erchius Fuel can be found beneath the surface of every moon. Survival on moons requires the Breathing EPP. On moons, you can get the Spooked Status Effect, which spawns Erchius Ghosts. Erchius Ghosts are invincible.