Air-breathing sophonts who find themselves on the Surface of the Shattered Moon should spend their few remaining minutes looking for Undershard Snails. I'm told that these hand-sized creatures produce enough air to keep you alive for up to an hour.
I've been told that using an undersnail is like breathing through someone else's stuffed-up nose. You'll live doing it, but you might not want to. Also, there's the risk of getting brain parasites, but an orc's got to breathe!
Undershard snails range in size from the width of the palm of your hand to a large dinner plate. They crawl on the bottoms of most Shards of Thaya feeding on algae and plants growing there. They commonly fall off the shards and drop to the Surface of the Shattered Moon, where they can survive by generating a micro-atmosphere within their shells.
On the surface colonies of them survive by feeding on detritus that falls from the shards above them, including their siblings who's shells weren't sturdy enough to survive the drop. Unless they're actively feeding, undershard snails on the surface, remain dormant to conserve energy and resources. They retract into their shells and generate a mucus plug that hardens into a protective trapdoor.
Dormant undershard snails come to life when they smell food or the vibrations of a vine dropping down from the shard above them. They eat their hardened mucus plug and slowly crawl towards the food source or the escape route from the surface. Undershard snails will eat anything organic, so travelers on the surface must be careful to brush them off any leather or wood they may be carrying with them. They must also be careful where they sleep lest they find themselves woken by dozens of hungry undersnails nibbling on their extremities.
Subsisting on Snails
For those who find themselves on the Surface, undershard snails are both a necessity and a nuisance. Each snail's shell contains up to an hour of breathable air in them. The trick is keeping the snail alive, so that it produces breatheable air, without it simultaneously eating your face. Those who know they're traveling to the surface bring special "snail spoons" with them that covers the undersnail's mouth and tentacles while allowing access to their air producing organs.
I've found myself on the surface without my magitech rebreather more than once and let me tell you, it's no picnic in the park. First you find an escargatoire and you pick the biggest snails that you can find. Then you crack open the mucus plug with a flat piece of metal, preferably a snail spoon, and cover up the rasps and the tentacles.
Then you get in there like you want a long-term relationship with this snail! That gets you about an hour worth of air, before the snail expires and you have to move on to the next one. Kinda reminds me of my love life!
Using an undershard snail like this is eventually fatal for the snail. However, the snails are edible (if disgusting) and sophonts have been known to live on a diet of them for a few days before being rescued or climbing back up a shard vine to the safety of the Mairun-sphere, the breatheable zone of air.
Beware Brain Parasites
Unfortunately for those surviving through the use of undersnails, a not insignificant portion of them are infected with brain parasites. Left untreated, the parasites can lead to swelling around the brain and spinal cord and madness. In the worst cases, the parasites lead to ceremorphosis, transformation into a mind flayer.