Unkei

Unkei, sometimes called netters, hunting aeronauts, or shroomballoons, are fungal creatures native to the planet Avatar, best known for their ability in adulthood to fill themselves with a lighter-than-air gas and float to surprising heights, and their literally networked pack behaviour. Avatar's thin atmosphere makes flight impractical for most large creatures, meaning that the apex predators of the air are tangles of slow-moving fungal balls, lashed together by lines of hyphae, sweeping the sky clean of insects, and sometimes lowering to engulf and feast on an unfortunate land animal.

In early life, an unkei spore will settle on an area of mulch and other nutrient-heavy parts of a forest's floor, and use those nutrients to grow its basic, balloon-shaped body. For the majority of its infancy, the balloon in question will be uninflated, little more than a caul drooping on the ground. Within a few days of its fruiting, the unkei gains a certain amount of motility. While it has almost no way to move its main body but for a slow, rolling shuffle, it does have the ability to shoot out strings of hyphae, which it uses to capture insects and small mammals to eat. The hyphae-shot contains enzymes that perform partial external digestion, and pull into chambers within the unkei's body where, by inflation and deflation of a ring of tough sacs, the animal to be consumed is crushed into slurry.

The unkei grows to its adult size very quickly and then spends a great deal of time seemingly not growing at all, as it busily develops its inflation organs. These stomachs draw in air from the atmosphere, mix it with internal fermentation and the flesh and plants the unkei eats, and create the lighter-than-air gas (a mix of many gases, prominently helium and methane) that will lift the unkei when it reaches that phase. Once the organs are fully developed, the unkei swells and grows over a matter of days if not hours, eventually reaching liftoff. During this period, it uses hyphae-shot to scour as much edible plant and animal matter as it can, taking advantage of its surprising access to previously safe creatures. Once an unkei is fully inflated, it requires little nutrition to sustain itself over a long period, and this lift-off harvest will sustain it for months.

The first flight of an unkei is rarely a calming thing to witness; when it expands, its previously bland outer mycellium lights up with a riot of colours, resembling huge, avid, and predatory eyes.

When airborne, unkei drift without direction, governed by wind and currents. When they find prey - high flying insects or treetop mammals - they gather them up with hyphae-shot. When they find other unkei, however, they use a variant, multi-cabled hyphae-shot that binds the two unkei together. This not only forms a pack, but will then become part of a web that can catch further prey and drag them into the unkei's waiting maws. Eventually, the massed unkei have not only a web, but something not unlike a sail, allowing slight control of their own movements. At this level, they take on another hunting behaviour; when they find that predators have freshly killed a large animal, they expel their gas in unison, collapsing on the kill to consume it en masse. It is at this point that the unkei's terrifying appearance shows its worth; very few predators hold their ground against a swarm of web-linked eyeballs farting from the sky. (Those that do can often get quite a good meal, if their digestive systems can process unkei 'meat'; unkei have little to no defence against even medium-sized creatures.) The unkei swarm will consume the prey and anything else coming to feed on it (and anything else in the area) over a matter of days, before abruptly reinflating and returning to the sky.

Unkei can live for a hundred years or more, though very few last past eighty. The most common symptom of unkei aging is the equivalent of autoimmune syndrome, where the inflation organs eat and rot at the unkei's flesh. If an unkei dies on the outskirts of a flight, the other unkei will sever their bonds with it and let it fall; a dead unkei in the middle of a flight, however, tends to remain suspended. A fairly common cause of death for unkei is to be part of a flight weighed down by too many corpses, unable to extricate themselves before suffering from the consequences of being trapped in place (anything from starvation to predation).

The presence of the unkei is typically thought to explain the natural piloting skills of the Soch-Metion species, believing it developed a symbiotic relationship between the Soch-Metions and the unkei, where Soch-Metion animal wranglers would create unkei-lifted airships to find food, explore new areas, and occasionally go to war with one another.