Elaysian homeworld

From Memory Alpha, the free Star Trek reference.

The Elaysian homeworld is a planet with very low gravity.

Only a handful of Elaysians have ever left the homeworld. Melora Pazlar was one of them. (DS9: "Melora")

Any planet with low surface gravity is unlikely to sustain a nitrogen/oxygen atmosphere; however Melora Pazlar breathes the same air as the other inhabitants of DS9. Thus we speculate that the Elaysians migrated to this world and now live in sealed environments on the planet surface similar to the Lunar colonies, yet without any artificial gravity system.

Apocrypha

Gemworld, Book 1 and 2 state that the Elaysian homeworld is Gemworld, a planet considered artificial by some, due to it should have been extinct long ago, but was kept alive with a "shell" forcefield and shield setup that also collect different chemicals and substances to convert into energy to feed the Crystal that is now all that is left of their planet. It concludes that Elaysian, Alpusta, Gendelli, and Yiltern were all transplanted from a different Dimension by the Lipul, oldest of the planets inhabitants. The Frills are also native to the planet.