Spelljammer had most of the moons given detail and some inhabitants. Look up Realmspace, Greyspace and Krynnspace.Right, so more of Lovecraft's dreamlands ideas - his critters populated the moon and so one could go there. It was populated by Moon Beasts (converted in Sandy Peterson's CoC/D&D great crossover material and probably elsewhere). They associate with Leng Spiders and folk of Leng....
I guess the geology could include large deposits of highly nutritious and valuable mineral-eating fungal/nonvascular plant material known colloquially as Green Cheese......
Anyone ever developed a setting for DnD on the moon?
I should have remembered that....Spelljammer had most of the moons given detail and some inhabitants. Look up Realmspace, Greyspace and Krynnspace.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.