On the Ecology of the Gelatinous Cube

"There is a great concordance in the universe, where many places possess the same result but with quite different causes. . ."
-Mordecai, Gahzan Royal Scribe

Nomenclature: Gelatinous Cube, Athcoid, Kyboid, Qulare, Geldra

Description: Coagulated viscous transparent  hexahedron

A list of rumors and facts regarding cubes and their purposes as codified by the alchemists and sages.

Things that are known:
  • Cubes may produce a pseudopod to attack
  • The touch of the gel causes paralysis
  • They absorb matter. Living matter is digested, non-living matter is eventually excreted.
  • The do not move very quickly
  • They are able to detect and respond to heat and vibration, and can alter their size to fit through cavities as small as 1'
  • They weigh upwards of 15,000 pounds

Things that are said:
  • They are not actually cube-shaped, they just expand to fill the available space
  • It maintains its shape due to filamentous internal fibers. When killed, these decay and it dissolves into a wet mess
  • They asexually reproduce by budding
  • In point of fact, they do not bud, but instead leave small gelatinous polyps
  • Cubes are highly intelligent creatures
  • If you try to trip a gelatinous cube, it is said to tear the fabric of reality
  • It's nonsensical to try and trip a gelatinous cube, but if you string razor-wire across a hallway, you can instead fight weakened gelatinous slices
  • Trying to slice a gelatinous cube apart won't work, because it will just join and reform again like a jelly
  • If you cut a gelatinous cube, the surface begins to bud madly, covered in disgusting polyps, each a baby gelatinous cube
  • They were created exclusively to make pit traps more deadly. They are less an independent creature and more a substance created just for pits
  • They are simply giant paramecium that have evolved to encompass their local space to compensate for their blindness
  • They have a deadly aversion to salt. Its use dries them out
  • They are devoid of any thought, simply being a manifestation of earth (making them immune to mind-affecting effects)
  • When they meet, they join, doubling in size, but later separate into two normal-sized cubes
  • They travel by sliding like a slug
  • They travel by rolling from side to side
  • Actually their skin has a variety of properties and they slide by changing the molecular surface of their surface to increase or decrease resistance, sailing along dungeon corridors
  • They don't actually move at all, they are all absolutely stable in relation to the universe, the universe moves around the cube. The result of all simultaneous cube movement is geography
  • The paralysis effect also anesthetizes prey
  • The acidic digestive properties are contained within movable elastic cavities inside the cube
  • They are said to evolve from Grey Oozes
  • They feed on emotions which strengthen them
  • If you feed the Gelatinous Cube different types of fungi, it grants the cube different powers, from regeneration to auras to magical effects. People who have experimented with this idea universally end up dead from the plague
  • They can be found underwater, but are more visible and have their paralysis abilities diluted (+6 to the save)
  • Gelatinous Cubes aren't really an ooze or jelly at all, but a broodmother of goblins. They bud, producing the menace. When goblins age, they crawl into a depression and liquify. When enough do this, it can create a new cube
  • The creature either has a very rapid adaptation process or dungeons have been around for a long, long time, on the order of 100,000 years or more
  • It is said that their are races mad enough to become gelatinous cube riders. They wear a ring that surrounds them in a bubble of force, and tempt the cube to absorb them. Once within, they direct the cube by slamming the bubble, causing it to move in the desired direction.
  • They are avatars of mechanus, a quasi-living engine designed to scour chaotic organic material from the surface of the earth
  • Cubes aren't actually living creatures at all, but a square vacuum held between the interfaces of seven dimensional bubbles. Touching the surface of these outer bubbles is what causes the paralysis, as you experience shock. It's not actually digestion, but the exposure to a freezing zero-pressure vacuum which causes it to break apart. This is also why metal and stone are unaffected
  • When killed it maintains its shape and paralytic propterties
  • They were originally designed as a healing aid to prevent disease and rot and as a sanitary measure. They eventually escaped and evolved into their current form
  • If you cut off a piece of a cube and cook it with a base such as quicklime, it renders the anesthetic properties inert. This produces a bland, nourishing, protein rich, translucent brown aspic. It is highly valued in subhuman tribes
  • Alchemist's have a need for Gelatinous Cubes because it enhances the process by which they can extract magical essences
  • Gelatinous Cubes are actually leftover material from the construction of the sky, making it theologically relevant
  • They smell of boiled cabbage
  • They are created by gathering minor demons (imps, quasits, etc.) and casting flesh to ooze upon them. The resulting gunk is treated with aboleth slime and purple worm extract before being poured into a mold, most commonly a 10' square wooden mold. 
  • They are not silent, when they attack they yell "Cube!"
  • Gelatinous Cubes can be captured and altered into other forms and creatures. 
  • It's an advanced trap, a container for minds. It intends to lure the party into a trap so that it can exchange minds with one of them
  • They communicate with each other by slamming on the ground, sending shock waves back and forth
  • The cubes aren't the size of the corridor because they have filled the space. The cubes adolescent stage is a rarely encountered Volcanic Cube that hollows out new dungeon corridors, deep within the earth.
  • On death they ossify and turn into giant cubes and shapes of bone. Sometimes their sides harden and pit, and giants collect them for use in divination and games
  • They have a membrane (skin) that holds their insides in. When killed, everything inside leaks out
The Gelatinous Cube
Number Encountered: 1 Attacks: 1
Alignment: Neutral Damage: 2d4+special
Movement: 60' Save: F2
Armor Class: 8 Morale: 12
Hit Dice: 4 Hoard Class: VII
Experience: 245

The nearly transparent gelatinous cube travels slowly along labyrinth corridors and cave floors, absorbing carrion, creatures, and trash. Inorganic material remains trapped and visible inside the cube’s body. A typical gelatinous cube is 10 feet on a side, though much larger specimens are not unknown. The translucent appearance of the gelatinous cube makes characters surprised on a surprise check roll of 1-4 on 1d6. A gelatinous cube attacks by slamming its body into its prey to engulf foes. This attack deals 2d4 hit points of damage, and an opponent must succeed in a saving throw versus paralyze or become paralyzed for 2d4 turns. The spell cure light wounds causes a character to regain movement, but this use does not heal hit points with the same casting. Subsequent attacks against a paralyzed foe always hit. Gelatinous cubes are immune to the effects of lightning and cold-based attacks. They take normal damage from weapons and fire-based attacks. (Labyrinth Lord OGL)

  • Umber (or dung) Cube: It is said that using these to dispose of waste in an earth closet causes this mutation. This is identical to the normal cube, except the stench within 10' requires a save versus poison (Fortitude save DC 20, Con based) or be nauseated. All successful attacks also require a save versus poison or gain a disease (Filth Fever)
  • Volcanic (or fire) Cube: This is a larval form of the cube. Being more dense it has between 4-6 hit dice. It does not paralyze but is resistant to physical damage, taking half damage from melee attacks. It is also immune to fire and has a fire aura, doing 2d4 points of damage to anyone within 10' and 1d4 points of damage to anyone within 20' as a wall of fire. These are never found except in the deepest corridors far away from wandering players. It breaks down the nuclear bonds between the material, fueling it's terrible growth.
  • Grey (or psionic) Cube: certain otherworldly experiments on crossbreeding cubes have given them psionic powers. In addition to their normal features, they have 60+6d10 power points, Attack Modes: B, E, and Defense Modes F, with the Disciplines: Dominate, Cell Repair (6* Hit dice in hit points a round)
  • Ebony (or black) Cube: Crossed with black puddings, these cubes are no longer transparent, but much more acidic. Their strikes also do an additional die of acid damage and have a chance of degrading armor, save versus paralysis or have your armor degrade by one category, from heavy to medium, or medium to light (DC 20 Reflex save or armor becomes broken). Weapons must also make this save.
  • Electric (or yellow) Cube: Can discharge an electric aura every 1-4 rounds, doing a die+2 damage to every target within 10' and causing them to be stunned. A save versus paralyzation will negate the stunning effect (DC 20 Fortitude save versus paralyzation)
  • Frost (or dirty white) Cube: A hybrid of brown mold, these cubes grow when exposed to heat and have an aura of cold doing 3 dice of subdual damage a round to anyone within 10'
  • Spell (or pink) Cube: This brain cube is brilliant and can cast spells.
  • Stunjelly (or dungeon) Cube: This is a cube that adapts by not being transparent, but by taking on the appearance of nearby walls. It smells of vinegar.


  1. Wow, this is amazing! Thanks, and I hope you do more of these in the future!

  2. Have you considered writing a bunch of these and publishing them?
    I'd love to have material like this to put to print.

  3. "The creature either has a very rapid adaptation process or dungeons have been around for a long, long time, on the order of 100,000 years or more"

    No, while using puddings and oozes in dungeons, there was always the problem that they could go everywhere. So a Mage or Master Breeder created this creature to clean only the special parts of the dungeons.

    I love this article and the pictures a lot.

  4. G+ Source


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