Cubifabrids
Cubifabrids are low-bodied, heavily plated earth elementals native to the volcanic vents of the Northern Maltreks. They graze on sulfurous, silica-rich mineral aggregates around fumaroles and hydrothermal fissures. Their bodies incorporate sulfur into a heat-producing metabolism and silica into a self-repairing ceramic shell. Bismuth and related heavy material are instead separated, refined, and expelled through an organ commonly called the ingot womb.
The two best-known cubifabrids are the social cubesmith, Cubifaber ordinatus, and the more territorial ingotback, Cubifaber effusor. Their raised-language genus preserves an older folk belief that the regular bismuth blocks found near cubesmith dens were the deliberate work of subterranean artisans. Comparative anatomy later extended the cubesmith’s name to its live-casting relative.
The Ingot Womb
Section titled “The Ingot Womb”An ingot womb is a thick-walled mineral organ connected to the cubifabrid’s furnace-gut. It removes bismuth from digested aggregate, transports it through heated channels, and gathers it around a reusable crystallization matrix. The organ is not reproductive. Its common name arose among miners who opened carcasses and found several metal blocks at different stages of formation inside a chamber that seemed to gestate and deliver them.
The organ’s ancestral function is safe purgation. Loose bismuth crystals would branch through and perforate the creature’s internal channels; concentrating the metal into compact forms allows it to pass without injury. Cubesmiths complete this process internally, producing regular blocks. Ingotbacks retain bismuth in a molten or semi-molten state and complete the casting outside the body.
Cubesmiths
Section titled “Cubesmiths”Cubifaber ordinatus lives in colonies around broad vent fields. Families arrange cooled cubes in communal middens, along den boundaries, and around nursery galleries. Their apparent workmanship gave the species its common and scholarly names. Although generally tolerant of people who keep beyond the nursery boundary, an adult can brace against the ground and launch a prepared block from its terminal tract. Miners call this defensive discharge a cloacal ballista.
Midden gathering can sustain a long relationship between a colony and a nearby settlement. Experienced gatherers watch the family’s movements, approach only cooled and abandoned deposits, and avoid taking blocks used to mark active passages. Regular disturbance, theft from nursery structures, or hunting turns an otherwise docile colony defensive.
Cubesmith Adult
Ceramic Carapace. The cubesmith has advantage on saving throws against effects that would move it or knock it prone. Its natural weapon attacks are magical.
Colony Defender. When an allied cubifabrid within 30 feet of the cubesmith is hit by an attack, the cubesmith can move up to half its speed toward the attacker. This movement does not provoke opportunity attacks.
Actions
Multiattack. The cubesmith makes one bite attack and one foreclaw attack.
Bite. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 15 (2d10 + 4) piercing damage.
Foreclaw. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 13 (2d8 + 4) slashing damage.
Cloacal Ballista (Recharge 5–6). The cubesmith launches a prepared bismuth cube at one creature it can see within 60 feet. The target must make a DC 15 Dexterity saving throw. On a failed save, it takes 27 (6d8) bludgeoning damage and is knocked prone. On a successful save, it takes half as much damage and isn't knocked prone. The cube lands in an unoccupied space within 5 feet of the target and creates difficult terrain in that space until moved.
Ingotbacks
Section titled “Ingotbacks”Cubifaber effusor retains processed bismuth in a heated reservoir and expels it across intruders and terrain. The metal lands dull and molten, then hardens into angular, iridescent castings. Ingotbacks use these discharges to seal passages, divide attackers, and defend routes into the family den.
Ingotbacks live in small family units rather than as strictly solitary animals. One adult ordinarily patrols the perimeter while the others forage, maintain galleries, and move the young away from danger. Miners usually call this defender the alpha. Naturalists prefer warding adult, since observation shows that warding is a rotating form of dangerous labor rather than a fixed dominance rank. The role may change with health, casting reserves, age, and the needs of the family.
Young cubifabrids cover a broad developmental range. Newly formed young have porous shells and no controlled casting. Older juveniles may leak or spit hot metal when frightened. Armored subadults have functional ingot wombs but produce shorter and less stable castings. Fully developed foraging adults can cast reliably, while a well-provisioned warder has the thickest plating and largest defensive reservoir.
Ingotback Warding Adult
Ceramic Carapace. The ingotback has advantage on saving throws against effects that would move it or knock it prone. Its natural weapon attacks are magical.
Siege Body. The ingotback deals double damage to objects and structures.
Warding Instinct. While the ingotback is within 60 feet of an allied cubifabrid that has fewer hit points than it, the ingotback has advantage on Wisdom (Perception) checks and can't be frightened.
Actions
Multiattack. The ingotback makes one bite attack and one foreclaw attack.
Bite. Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 16 (2d10 + 5) piercing damage.
Foreclaw. Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 14 (2d8 + 5) slashing damage. If the target is Large or smaller, it must succeed on a DC 16 Strength saving throw or be pushed up to 10 feet.
Molten Casting (Recharge 5–6). The ingotback braces and expels molten bismuth in a 30-foot-long, 5-foot-wide line. Each creature in the line must make a DC 15 Dexterity saving throw, taking 28 (8d6) fire damage on a failed save, or half as much damage on a successful one. On a failed save, a creature is also restrained by rapidly cooling metal. A restrained creature can use its action to make a DC 15 Strength (Athletics) check, freeing itself on a success. The casting around one creature can also be destroyed (AC 17; 20 hit points; immunity to poison and psychic damage; vulnerability to thunder damage).
The line remains until cleared. Its spaces are difficult terrain, and a creature that enters one of those spaces for the first time on a turn or starts its turn there takes 5 (1d10) piercing damage. A 5-foot section has AC 17 and 20 hit points and shares the casting's immunities and vulnerability.
Ingotback Foraging Adult
Ceramic Carapace. The ingotback has advantage on saving throws against effects that would move it or knock it prone. Its natural weapon attacks are magical.
Actions
Multiattack. The ingotback makes one bite attack and one foreclaw attack.
Bite. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 15 (2d10 + 4) piercing damage.
Foreclaw. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 13 (2d8 + 4) slashing damage.
Molten Casting (Recharge 5–6). The ingotback expels molten bismuth in a 20-foot-long, 5-foot-wide line. Each creature in the line must make a DC 15 Dexterity saving throw, taking 21 (6d6) fire damage on a failed save, or half as much damage on a successful one. On a failed save, a creature is also restrained by rapidly cooling metal. It can use its action to make a DC 14 Strength (Athletics) check, freeing itself on a success. The casting can also be destroyed (AC 16; 15 hit points; immunity to poison and psychic damage; vulnerability to thunder damage).
Ingotback Armored Subadult
Ceramic Carapace. The ingotback's natural weapon attacks are magical.
Actions
Multiattack. The ingotback makes one bite attack and one foreclaw attack.
Bite. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 12 (2d8 + 3) piercing damage.
Foreclaw. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 10 (2d6 + 3) slashing damage.
Unstable Casting (Recharge 5–6). The ingotback spits hot bismuth in a 15-foot cone. Each creature in that area must make a DC 13 Dexterity saving throw, taking 18 (4d8) fire damage on a failed save, or half as much damage on a successful one. On a failed save, the creature's speed is reduced by 10 feet until the end of its next turn as brittle metal hardens around it.
Age, Family, and Death
Section titled “Age, Family, and Death”Elderly cubifabrids are uncommon. Territorial challenges, competition between families, ingot-womb impaction, and declining control over crystallization all contribute to their scarcity. Human hunting has distorted the pattern further: old warders are exposed at vent boundaries, and mature ingot-womb matrices command the highest prices. Communities that protect cubifabrids report elders remaining with families after leaving the warding role, contradicting the widespread mining claim that every old “alpha” is violently expelled.
A cubifabrid’s death ends the elemental maintenance that holds its heated composite body together. Fresh carcasses cool unevenly, vent sulfurous gas, and produce audible pings as ceramic plates crack or spall. Miners say such a body is still ringing and wait before approaching it. Once cooled, the porous internal matrix crumbles and leaves a hollow ceramic shell reinforced by glassy seams.
Families reclaim much of this material. Plates may be consumed for silica, fitted into unstable vent walls, or used to shelter young. A long-serving warder’s shell can gradually become part of the den entrance. Whether repeated guarding and touching of particular remains constitutes mourning remains a matter of naturalist debate.
Material Uses
Section titled “Material Uses”Naturally purged bismuth is a useful specialty metal rather than a precious one. Its purity and low working temperature make it valuable for casting, alloys, pigments, and alchemical reagents. The carcass offers additional materials:
- dense outer plates provide refractory ceramic for kilns, furnaces, and crucibles;
- smooth inner glaze can be remade into chemically resistant ventglass;
- thin joint scales serve as overlapping heat guards;
- glassy silica seams fracture into extremely sharp knives, scrapers, and points.
Legitimate shellers salvage naturally dead animals only after the body has finished ringing. Hunter-miners often carry seamknives and shell armor made from earlier kills, equipment that living cubifabrids may recognize as a threat.
Kalassarian Use
Section titled “Kalassarian Use”During the Kalassarian Golden Age, Northern Maltrek settlements developed a mixed cubifabrid economy. Some tended vents, provisioned mineral aggregate, gathered abandoned middens, and salvaged naturally cooled shells. Others hunted cubifabrids or supplied an illegal trade in womb-cut metal and intact organs. Near the end of the period, a small number of alchemical institutions began experimenting with captivity and the use of living cubifabrids as biological refineries.
The surviving evidence is uneven. A tended midden, hunting camp, shellworking floor, ritual image, or experimental enclosure preserves only one part of the relationship. Structures first attributed entirely to Kalassarian industry have sometimes proved to contain walls and shelters assembled by the animals themselves. Conversely, sites remembered as harmless midden grounds may conceal opened carcasses and alchemical workrooms.
Cubifabrids never vanished from the Northern Maltreks. Local gatherers and craftspeople continued to use their middens and shells after the wider Kalassarian system fell from memory. Current scholarship is rediscovering the historical importance of practices that mountain communities continued in more ordinary forms.
Alchemical Exploitation
Section titled “Alchemical Exploitation”The greatest alchemical demand is not for bismuth but for the ingot womb. The organ separates one substance from a mixed aggregate, controls heat and phase, establishes a repeatable crystal matrix, and survives repeated casting cycles. Alchemists have sought to reproduce these functions in the hope of purifying magical alloys, preserving unstable reagents, or separating a magical property from its native tissue.
Midden collection can support a cubifabrid family for generations; removing an ingot womb kills the animal and often destroys the family structure protecting the vent. This difference has produced a long conflict between midden gatherers, vent-tenders, carcass salvagers, hunters, and the organ traders known as womb-cutters.