system
Given the following post, respond as if you're commenting on Reddit:
human
Do we know of a "gas-moon"?

Is there any moon, orbiting a planet, which is made out of gas, instead of rock, that we know of?
gpt
No, we haven't detected any exoplanets with moons and none of our solar systems moons are gaseous (mostly rock, one that's mostly ice/water).

It is also difficult to believe that such an object would be possible. The reason why the outer planets have such thick atmospheres is a result of their size. By the time you are massive enough to be a Gaseous body you are likely just a planet.