Gelatinous cube

A gelatinous cube, also known as an athcoid, was a transparent ooze composed of mindless, gelatinous matter in the shape of a cube or rhombohedron. They were especially favored by the drow god Ghaunadaur.

"The dungeon's floors were spotless. That should have been our first clue."

- Jaster Hollowquill, on his exploration of Undermountain.

Description
Typically, a gelatinous cube measured between on a side and weighed as much as,  although legends existed of much larger cubes. The creature was completely transparent, with only a glint of its surface in the light to give away its position. The occasional random object floating in a well fed gelatinous cube's body could also serve as a warning of its presence to dungeon delvers.

Gelatinous cube bodies were remarkably moldable. They could flow around objects and through narrow passages, quickly returning to their shapes once enough space was available.

Behavior
A gelatinous cube was a mindless predator that silently roamed ancient crypts and vaults in regular, predictable patterns. As they traveled the halls of old ruins, they absorbed any material in their paths from the floors and walls. Although incapable of climbing walls, particularly large gelatinous cubes could also absorb mold and moss from ceilings. Organic material was quickly dissolved in the acidic ooze that made up the cube's body, while bones and inorganic matter spent some time floating within the creature until eventually expelled. As they slid through the corridors, they left behind a perfectly clean path, except for an occasional slimy trail.

Abilities
Gelatinous cubes could not see or hear, but were capable of sensing vibrations and were attracted to warmth.

Combat
When facing an opponent, a gelatinous cube could slam it with an acidic pseudopod or attempt to engulf it. It was possible, although difficult, for sufficiently strong creatures to escape engulfment by a gelatinous cube. Despite their slow speed, gelatinous cubes were strong and could easily push back and knock over even large creatures.

When touching a creature, gelatinous cubes secreted a gummy paralyzing substance that was immediately absorbed through the skin into the victim's bloodstream. After successfully engulfing a victim, the cube moved pockets of an acidic digestive substance towards the victim's body, quickly digesting it. Survivors of gelatinous cube attacks displayed scars that resembled partially melted wax.

Regardless of their sizes and homogeneous composition, gelatinous cubes were vulnerable to most usual forms of attack, although reports existed of cubes that were immune to electricity. Mind-altering effects were useless against the mindless creatures. Some were said to be slowed down by cold-based spells.

Diet
Gelatinous cubes were omnivorous scavengers.

Despite being extremely effective against flesh and cellulose, the digestive fluid of gelatinous cubes had no effect on inorganic matter or bones. Any inorganic matter would remain within their bodies for several weeks until eventually being cast out.

Reproduction
Gelatinous cubes reproduced asexually by either dividing themselves into two smaller cubes of equal sizes or via budding. In the second case, a smaller, rubbery cube was excreted into a side corridor or on a pile of refuse, and left to fend for itself until it grew into a full-sized cube. These smaller cubes were not cared for and ran the risk of being absorbed by their own parents on their next trip down the corridor. Surviving young cubes then rapidly grew to adult sizes.

When two gelatinous cubes met, they could temporarily fuse into a larger form that acted like a single creature. They could remain in that fused form for up to a few days before splitting and going their separate ways.

Habitats
These creatures were typically found inhabiting underground locations or dungeons. They were more common in heavily frequented dungeons, attracted by the more readily available food and carrion.

Uses
Some creatures considered gelatinous cubes to be ideal means of cleaning out their dungeon lairs of all manner of organisms. Some tried to cultivate larger cubes in order to ensure that they could reach mosses or similar organisms that collected on ceilings.

History
According to the Demonomicon of Iggwilv, gelatinous cubes and other oozes were either fragments or the spawn of Juiblex. While this claim was not widely believed, the demon lord could exert control over them, imbuing them with a sense of purpose and even intelligence.

The Imperial Zoo of Amn successfully kept a gelatinous cube in captivity for about 12 years in the mid‒14 century DR.

The adventurer Haptooth claimed to have developed an oral antidote against the gelatinous cube's paralyzing secretion after years exploring Undermountain.

The Waterdhavian dungeon complex of Undermountain contained numerous gelatinous cubes. In the late 15 century DR, the wizard Halaster Blackcloak, while experimenting with the duergar ability to enlarge their bodies, created a giant gelatinous cube that measured on a side.

Notable Gelatinous Cubes

 * Glabbagool, a sentient gelatinous cube who lived in the Underdark sometime in the late 1480s or 1490s DR.

Appearances

 * Adventures
 * Dungeon #30, "…And a Dozen Eggs" • Curse of the Azure Bonds • Hellgate Keep • Expedition to Undermountain • Out of the Abyss • Waterdeep: Dungeon of the Mad Mage
 * Novels
 * Masquerades
 * Gamebooks
 * Escape the Underdark
 * Video Games
 * Eye of the Beholder II: The Legend of Darkmoon • Baldur's Gate: Dark Alliance  • Neverwinter Nights  • Sword Coast Legends  • Idle Champions of the Forgotten Realms
 * Card Games
 * AD&D Trading Cards • Dragonfire