Annonymous asked over on Tumblr

You mentioned that your sophonts have pouches. Would mannuls have pouches facing their tail to prevent water getting in it like thylacines?

2026 -
Their upright locomotion and height, and how maanuls are from open areas with low vegetation, do not require their pouch to be at the rear to prevent debris from getting in like thylacines do. To prevent water from entering their pouch, maanuls have a strong ring of muscle, a sphincter, to make it water-tight. Like a water possums!
It is at their lower stomach because they also need easy access to it, for grabbing their young in and out, and other basic social interaction between the parent and the fledgling for bonding. But most importantly, they need easy access for egg transfer.

The biological family the sophonts of altuyur are a part of, lies a soft, basically a meat egg / amniotic sac, onto their hands before rapidly transferring it into their pouches. If the egg is not transferred, it dries up, or other damage happen because of the sun's UVs, causing death for the embryos.
The transfer triggers "gestation," where the pouch itself seals, not through muscle sealing as it would cause strain during extended periods of time, but through the growth of tissues at the entrance, and all around the egg sac. The membrane is pierced by the hatclings or cut by the parent if the baby is unable to do it themselves once gestation is over. The pouch is basically an external womb first, then later becomes a transport pouch for the striped fledglings.
(Though I say they lay into their hands, this isn't possible for mierthri's anatomy. They require external help from entourage/direct family to do so. Out of the 3, theirs is pretty difficult, while maanul probably has it the "easiest".)

Maanuls pouch is still positioned much lower than what the other two sophonts have; Mierthri has it at the highest because interactions are mainly with their jaws and not their hands, which are not very good at being manipulators. Maanuls and kyhuines will sit on their rear in order to access their pouches easily, though they are capable of bending their bodies around to do so (more flexible than you think!), it is not the most comfortable and safe way to do so.

Now, why does the biological family have this complicated cycle that involves extra steps instead of just having a full gestation internally? Millions of years ago, before any of the sophont's recent ancestors were even a possibility yet, they used to be specialised in brood parasitising a now extinct family of distantly related species. As the species they preyed upon became rarer, individuals developed temporary pouches of folded skin, similar to what echidnas do, to carry the egg before they eventually found their target. This turned into a permanent, all-year-round pouch that they rely on as they had to abandon the parasiting as the targets went extinct.
There was a split in the family where some just kept the egg inside the body until it hatched, while others became pouch reliant. The sophonts of Altuyur, are a part of the pouched group.