Aigéad Fuil

Aigéad Fuil
On the former Hive World, now turned Death World of Aigéad Fuil, a single settlement, protected by void shields exists on this world, has a burgeoning society of techno-barbaric gangs. They are allowed to commit their gang warfare in the trade city as long as they don't attack off-worlders and give a tithe to the Astartes overlords. The Techno-Barbarians use armored vehicles, and scavenge from failed recon teams and aircraft from the wastelands due to the acidic atmosphere. But the risks of these expeditions and the rapidly degrading hulls of the vehicles cause inter-gang warfare, as gangs fight for loot and intact hulls for their own craft.The hardened youth, with an experience of armored warfare and technological expertise are perfect candidates for the Astartes. The ancient hives that eked out a harsh living on the acid-rain soaked planet of Aigéad Fuil was brought into the Imperial Fold, and would be gifted to the Bloodmoon Hunters Chapter for overseeing the warp routes further into the Ishtar Fringes that would become known as the Sanguis Portus, or the "Blood Gate". Few others make life out of heavily processed ancient lower hives of hives whose void shields has failed over time.

With hostile atmosphere and frequent tectonic shifts, the survivors to take particular care about their airtight environment, oxygen rationing, geothermal energy and the fragility of the tectonic plates. They are hardy folks, who use a lot of breathing suits, have great knowledge of mineralogy and technically competent on a level of your standard Forgeworlders. The need for everyone to know how to replace air-filters. The great subterranean hive and former great subterranean hives of Aigéad Fuil are a reverse of a typical hive. The lowest reaches of the hives are the safest where the techno-barbarians have some organization and security but the upper hives where scavengers prey is where the lawless infest to get the limited supplies from the only working space port.

Biosphere
Sulfuric acid is produced in the upper atmosphere of Aigéad Fuil by the Sun's photochemical action on carbon dioxide, sulfur dioxide, and water vapor. Ultraviolet photons of wavelengths less than 169 nm can photodissociate carbon dioxide into carbon monoxide and atomic oxygen. Atomic oxygen is highly reactive. When it reacts with sulfur dioxide, a trace component of the Aigéad Fuilian atmosphere, the result is sulfur trioxide, which can combine with water vapor, another trace component of Aigéad Fuil's atmosphere, to yield sulfuric acid. In the upper, cooler portions of Aigéad Fuil's atmosphere, sulfuric acid exists as a liquid, and thick sulfuric acid clouds completely obscure the planet's surface when viewed from above. The main cloud layer extends from 45–70 km above the planet's surface, with thinner hazes extending as low as 30 km and as high as 90 km above the surface. The permanent Aigéad Fuilian clouds produce a concentrated acid rain, as the clouds in the atmosphere of Earth produce water rain.

The atmosphere exhibits a sulfuric acid cycle. As sulfuric acid rain droplets fall down through the hotter layers of the atmosphere's temperature gradient, they are heated up and release water vapor, becoming more and more concentrated. When they reach temperatures above 300 °C, sulfuric acid begins to decompose into sulfur trioxide and water, both in the gas phase. Sulfur trioxide is highly reactive and dissociates into sulfur dioxide and atomic oxygen, which oxidizes traces of carbon monoxide to form carbon dioxide. Sulfur dioxide and water vapor rise on convection currents from the mid-level atmospheric layers to higher altitudes, where they will be transformed again into sulfuric acid, and the cycle repeats.

Sulfuric acid is formed naturally by the oxidation of sulfide minerals, such as iron sulfide. The resulting water can be highly acidic and is called acid mine drainage or acid rock drainage. This acidic water is capable of dissolving metals present in sulfide ores, which results in brightly colored, toxic streams. The oxidation of pyrite (iron sulfide) by molecular oxygen produces iron.

History
During the time before the Horus Heresy, Aigéad Fuil was a Icy Hive World where the air was sulfuric and an outpost of the Death Guard Legion. Here they stored great many munitions for the wars to be conducted on the Imperium's behalf. The Ultramarines sent a fleet to exterminate the planet to deny the enemy their munition stocks. Upon arriving to Aigéad Fuil, the Ultramarines committed to Exterminatus via Tectonic bombing. During the Exterminatus of the planet, the Pharos gets activated and the Ultramarines make way for Macagge at fastest possible speed, missing the fact a few Hives survived. Throughout the Heresy records of this incident and even the world of Aigéad Fuil get destroyed. This left this world lost along with the worlds beyond the Sanguis Portus. For the next several thousand years this world was forgotten by time.

Next when the Imperium rediscovered the Damuterr System, the world of Aigéad Fuil was a much harsher world with Tectonic instability and acidic atmosphere. The surviving hives had to be brought into compliance. This action was done by the newly founded Bloodmoon Hunters Chapter in M35. During the Compliance Action tradegy struck when containment on one of the vaults of the Death Guard was broken causing a mutagenic outbreak. In response the entire chapter was called to deal with the fighting. Over the course of fighting the mutagen infected Hive the Command and veterans of the Bloodmoon Hunters were falling in droves. In a desperate act to contain the threat Artificer Folsom deactivated the Void Shields of the Hive. The Acid of Aigéad Fuil destroyed all who had remained in the Hive.

The rest of the War of compliance was directed at the senior most person left, Artificer Folsom. Through use of ambush tactics and small unit fighting in the great tunnel systems, he claimed the world for the Bloodmoon Hunters.

Flora & Fauna
=Smugairle Aigéad= The Smugairle Aigéad concentrates sulfuric acid in cell vacuoles. The primary function of the accumulated acid in the Smugairle Aigéad's life history is unknown.It is thought to provide an important ecological defense.

The Smugairle Aigéad mainly free-swimming/flying atmosphere animals with umbrella-shaped bells and trailing tentacles, although a few are not mobile, being anchored to the ground by stalks. The bell can pulsate to provide propulsion and highly efficient locomotion. The tentacles are armed with stinging cells and may be used to capture prey and defend against predators. Smugairle Aigéad have a complex life cycle; the medusa is normally the sexual phase, the planula larva can disperse widely and is followed by a sedentary polyp phase.

The main feature of a Smugairle Aigéad is the umbrella-shaped bell. This is a hollow structure consisting of a mass of transparent jelly-like matter known as mesoglea, which forms the hydrostatic skeleton of the animal. 95% or more of the mesogloea (the tissue that functions as a hydro-static skeleton) consists of Concentrated Sulfuric Acid, but it also contains collagen and other fibrous proteins, as well as wandering amoebocytes which can engulf debris and bacteria. The mesogloea is bordered by the epidermis on the outside and the gastrodermis on the inside. The edge of the bell is often divided into rounded lobes known as lappets, which allow the bell to flex. In the gaps or niches between the lappets are dangling rudimentary sense organs known as rhopalia, and the margin of the bell often bears tentacles.

=Aiteann Péisteanna= Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are made of chitin. Aiteann Péisteanna are segmented worms, generally less than 10 cm (4 in) in length, although ranging at the extremes from 1 mm (0.04 in) to 3 m (10 ft). They can sometimes be brightly coloured, and may be iridescent or even luminescent. Each segment bears a pair of paddle-like and highly vascularized parapodia, which are used for movement and, in many species, act as the worm's primary respiratory surfaces. Bundles of bristles, called setae, project from the parapodia.

However, Aiteann Péisteanna vary widely from this generalised pattern, and can display a range of different body forms. The most generalised polychaetes are those that crawl along the bottom, but others have adapted to many different ecological niches, including burrowing, swimming, pelagic life, tube-dwelling or boring, commensalism, and parasitism, requiring various modifications to their body structures.

The head, or prostomium, is relatively well developed, compared with other annelids. It projects forward over the mouth, which therefore lies on the animal's underside. The head normally includes two to four pair of eyes, although some species are blind. These are typically fairly simple structures, capable of distinguishing only light and dark, although some species have large eyes with lenses that may be capable of more sophisticated vision.

The head also includes a pair of antennae, tentacle-like palps, and a pair of pits lined with cilia, known as "nuchal organs". These latter appear to be chemoreceptors, and help the worm to seek out food. Once finding food colonies of the Aiteann Péisteanna would leap or make way to the food source using Sulfuric Acid mucus to break down a creature for them to feed. Generally it will burrow inside a creature and eat from the inside out.

=Damhán Alla=

Damhán Alla are tube-dwelling spiders that construct rudimentary trap-doors. They spend most of their time here and are rarely seen above ground. The medium to large spiders range from eight to twenty-three meters long. They are characterized by their downward pointing, daggerlike chelicerae, and the segmented series of plates on the upper surface of the abdomen. The carapace is mostly flat, though it can be slightly elevated near the head. The eyes are distinctly clustered together on a single nodule. Anterior median eyes are small, but posterior median eyes are large and round. The lateral eyes are long and kidney-shaped. The distal leg segments have strong spines and three claws. Chelicerae are vertically attached to the cephalothorax. In the past, they were frequently believed to lack venom, but it was shown that at least some Damhán Alla species have venom glands.

They are active at night and live for many years. Although most species live in burrows, cave-dwelling species also fasten their retreats to the cave walls. Both burrows and retreats are sealed with woven doors. Trapdoor nests are generally built in shady areas with moss or sparse vegetation. Some make silk trip-lines radiating away from the burrow entrance. Adult males sometimes wander in search for females, but females rarely leave their burrows. The respiratory system consists only of book lungs, which could help explain why they are relatively inactive.

=Léim Portán=

Léim Portán do not build webs to trap prey, though all of them produce silk for drop lines and sundry reproductive purposes; some are wandering hunters and the most widely known are ambush predators. Some species sit on or beside Fungi, where they grab visiting creatures. Individuals of some species are able to change color over a period of some days, to match their surroundins on which they are sitting. Some species frequent promising positions where they await prey, and some of them sit in the open, where they are startlingly good mimics.

Other species of Léim Portán with flattened bodies either hunt in the crevices or shelter under such crevices by day, and come out at night to hunt. In each case, Léim Portán use their powerful front legs to grab and hold on to prey while paralysing it with a venomous bite. Some Léim Portán hunt other spiders and creatures in ways that seem intelligent, outflanking their victims or luring them from their webs. Laboratory studies show that Léim Portán's instinctive tactics are only starting points for a trial-and-error approach from which these spiders learn very quickly how to overcome new prey species.