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    Default Ecology of the Rust Monster Re-imagined [3.5 monsters]

    Ecology of the Rust Monster


    Rust monsters are an evolutionary anomaly; the only known creature that is able to derive sustenance almost entirely from metal. As such, their origins have seen significant debate among sages and adventurers. How did something this aberrant come to exist?

    A number of hypotheses have been advanced over years of research. Some scholars argue that rust monsters were bred by ancient wizards, perhaps to serve as guard beasts, to dispose of metallic waste, or to aid in arcane experiments. Others argue that they are creatures from a distant world where metallic-based life-forms proliferate.

    Recent research points to genetic links between rust monsters and common ants. Even a superficial look at their anatomy bears this out; their chitinous bodies, powerful mandibles, insectoid legs, and prominent antennae all hint at formicid ancestry.

    These links are obviously distant; a modern rust monster bears only the faintest similarity to an ant. Something in the distant past must have shunted these creatures from one evolutionary path and started them on the developmental road that led to their current form. The most common hypothesis is a catastrophic outpouring of chaotic or magical energy that altered the basic genetic information of the rust monster’s ancestor. Many sages venture additional details, hypothesizing that this cataclysmic event affected colonies of ant-like insects living in rock and soil with very high iron content, incorporating the metallic traces in the surrounding sediment into the genetic material of the mutated creatures and enabling the creation of the rust monster’s unique gastro-intestinal system.

    Rust Monster Evolution in the Scroungers Campaign Setting

    Like many other aberrations in the Scroungers setting, rust monsters arose in the years following the Torrent. Sages believe that their progenitors were colonies of ants living near areas of volcanic activity. Noting the frequent association of volcanic activity with both metal and go-stone deposits, scholars argue that these ant colonies were exposed to massive amounts of go-stone, resulting in changes to their basic biology similar to (though on a vastly greater scale than) those associated with Altered individuals. It is no coincidence that rust monsters survive by consuming metal; the volcanic locations where go stones are so often found are also often rich in metal deposits. Scholars believe that the metals in the soil and bedrock that surrounded the colonies of the rust monsters' progenitors were incorporated into their bodies by the go-stone energy, creating the rust monsters' unique physiology

    On first glance, rust monsters appear strange but not particularly remarkable. Their stubby quadruped bodies are covered in a segmented, rust-red chitinous carapace that stretches from their flattened face to the tip of the fan-like protrusion at the end of their long, muscular tails. Their four legs end in powerful claws for gripping and climbing and splay outward in an insect-like fashion, keeping their bodies low to the ground as they scuttle through tunnels and squeeze into tight spaces.

    Beyond these broad strokes, however, the specific adaptations of their unique physiology become apparent. This is particularly the case with close examination of their faces. Their mandible-like jaws contain heavy, dull teeth perfectly suited to grinding shards of rusty metal into pieces small enough to be swallowed. Their corrosive antennae, for which they are most famous, sit on either side of these mandibles. These antennae are typically about half the length of the rest of the rust monster’s body and covered in feathery protrusions that enable the creature to sense the presence of metal. They are also replete with pores from which a unique rust-inducing chemical is discharged.

    Internally, rust monster physiology is similarly unique, even in a world populated with strange and magical creatures. A rust monster’s gastro-intestinal tract is specially adapted to deriving sustenance from iron, tin, and other metallic substances. Their intestines are far longer than creatures of similar size, allowing shards of metal to pass more slowly through the digestive tract where they are subjected to wave after wave of digestive enzymes. These enzymes are produced in special glands located throughout the rust monster’s body. Their internal organs are also more resistant to cuts and punctures than other organisms, allowing them to cope with the jagged edges of the metal they consume.

    Life Cycle

    Rustlings, as rust monsters in their larval stage are known, hatch from eggs laid in large broods. These eggs, like so many things associated with rust monsters, are composed primarily of metal. In this case, the eggs’ shell is a thin layer of dissolved and partially-digested rust mixed with a special enzyme that causes the metal particles to adhere before drying out to create a brittle shell.

    Rustlings in a single brood hatch at more-or-less the same time, gnawing their way through the egg shell which serves as their first meal. They are completely blind except for their ability to detect metal, which allows them to “see” metal objects within roughly 30 feet. Nonetheless, they are extremely vulnerable; only the fortunate and strong survive to become rust monsters.

    After a few weeks, the rustlings are ready to metamorphose into their adult form. Once again, they cocoon themselves in partially-digested metal and rust and enter a brief state of hibernation. When they emerge, they are adult rust monsters or (much more rarely) adult rust monarchs.

    Rust monsters are not particularly long-lived. After a few weeks in their larval rustling stage followed by several days of hibernation, they live between 2 and 3 years as adult rust monsters. Their unique digestive system is also their ultimate downfall. As they age, their metabolisms slow, along with the processes by which metals are broken down and consumed by their cells. More and more intact metal molecules make their way into the rust monsters systems, using the very mechanisms by which they had been digested to incorporate themselves into the cells of the rust monsters’ carapace. As a rust monster ages, the carapace slowly turns to metal, eventually becoming a perfectly-preserved hollow iron rust monster husk before being consumed in turn by the surviving members of its mine. These husks are very thin and brittle, weighing approximately one fifth of the rust monster's weight while alive.

    Rust monarchs, the queens of rust monster mines, live far longer than their rust monster children, up to 15 years. As each rust monster mine consists of a single rust monarch and her offspring, the survival of the monarch is crucial to the survival of the mine. A sufficiently long-lived rust monarch can re-start the mine over and over, moving to new locations after one mine dries up or catastrophe strikes.

    Ecology and Behavior

    Rust monsters live in groups called mines. Each mine consists of a single rust monarch and her children. At any given time, the typical mine will number 7 or more adult rust monsters (including the monarch) and a large number of rustlings. It is not uncommon, however, for these numbers to be significantly higher.

    Rust monster mines are almost always located near a naturally-occurring source of metal ore. They prefer ferrous metals but can consume metal of any type. They construct elaborate tunnel systems as they extract more and more metal for consumption. Typically, a rust monarch and whatever rust monsters accompany her (usually only one or two) will arrive at a new source of food and begin to consume easily-available ore on or near ground level. As they consume, the absence of metallic extrusions weakens the surrounding rock, allowing them to begin to tunnel under the earth as they construct a more secure mine and continue to search for more food. They continue to consume and dig as long as there is adequate metal to support the mine’s numbers, only moving if the food supply is consumed or some new danger threatens the mine.

    A rock outcropping showing the effects of rust monster feeding habits.

    Rust monsters are not particularly intelligent. Most of their daily activity focuses on finding food and expanding the mine. They single-mindedly pursue any metal objects that they sense. Rust monarchs are slightly more intelligent. They typically wait a moment to ascertain the danger in pursuing a metal object or intruder, often sending their children head to investigate and backing them up with their special abilities.

    Rust monsters communicate mostly through movement. Their elaborate dances, supplemented with striking their tails on metallic surfaces or on their own bodies, allow them to communicate fairly complex concepts, though most rust monster communication is unidirectional from the rust monarch to her children. In the absence of a rust monarch, rust monsters seldom resort to this sort of communication, acting more-or-less independently. Rustlings have not been observed to communicate at all, acting blindly and without direction in all circumstances.

    Rust Monster Arcanoeconomics

    Body parts from dead rust monsters have a number of uses, both mundane and magical. The iron husks of rust monsters who died from old age are valued by collectors, museums, and scholars as decoration and as objects worthy of study. An intact husk with no obvious damage can be sold for approximately 500 gp to the right buyer. Finding an interested collector can be difficult, requiring a DC 20 Gather Information or Knowledge (local) check.

    Spell Components
    A successful DC 20 Knowledge (dungeoneering) check allows a caster to use a single rust monster antenna as an optional material component for the Rusting Grasp spell. If used, the antenna increases the spell's caster level by 1. It also allows the spell to affect magical items, though they are allowed a Reflex save against the spell's DC to negate the effect.
    Cost: 350 gp per antenna

    Rust Monster Carapace Armor
    The carapace of a single rust monster can be used to craft one of the following for a Medium creature: a suit of hide armor, a suit of scale mail, a breastplate, or a light or heavy shield. A suit of armor or shield constructed of rust monster carapace has the same basic statistics as a mundane version of the same item. It is always crafted as a masterwork item. Additionally, each time the user of an item crafted of rust monster carapace is hit with a metal weapon or a weapon with a significant metal component (such as a spearhead or ax blade), the weapon takes 1d3 points of damage. This damage ignores the hardness of the weapon.
    Cost: base armor/shield cost + 5000 gp
    Craft (armorsmithing) DC: 25 + AC bonus, 5 or more ranks in Knowledge (dungeoneering) grant a +2 synergy bonus on this check.

    Domesticated Rust Monsters
    A rust monster (not a rust monarch) can be taken as a rustling and raised with a modicum of domestication with a DC 25 Handle Animal check. Domesticated rust monsters must still be kept away from metal as much as possible. They are most often trained for fighting, guarding, and hunting.
    Cost: 1000 gp
    Last edited by Mephibosheth; 2013-02-12 at 11:28 AM.
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