Moon

The Moon controlling the water cycle of the planet of Moontides.
Over eons, some of the water from Moontides made it to Moon itself and formed a pool on the pole of the Moon facing the planet. Over generations, this pool provided an ecosystem of life to develop, especially with some of it being seeded by microorganisms carried in the water transferred from the planet. This evolution continued until the eventual emergence of the Luminaries and founding of Haven.