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Gelatinous Cube

Gelatinous Cube CR 3

Bits of broken weapons, coins, and a partially digested skeleton are visible inside this quivering cube of slime.

XP 800
N Large ooze
Init +0; Senses blindsight (thermal) 60 ft., sightless; Perception +8


EAC 13; KAC 15
Fort +5, Ref +3, Will +0
Immunities electricity, ooze immunities


Speed 15 ft.
Melee slam +11 (1d6+7 A and B)
Space 10 ft.; Reach 5 ft.
Offensive Abilities engulf, paralysis


Str +4, Dex +0, Con +2, Int —, Wis +1, Cha –4
Skills Stealth +13, Survival +8
Special Qualities transparent


Acid (Ex)

A gelatinous cube’s acid does not harm metal or stone.

Engulf (Ex)

Although it moves slowly, a gelatinous cube can simply engulf Large or smaller creatures in its path as a standard action. The gelatinous cube merely has to move over its opponents, affecting as many as it can cover. Opponents can make attacks of opportunity against the cube, but if they do so they are not entitled to a saving throw. Those who do not attempt attacks of opportunity can attempt a DC 12 Reflex save to avoid being engulfed—on a success, they are pushed back or aside (opponent’s choice) as the cube moves forward. Engulfed creatures are subject to the cube’s paralysis and damage from its slam attack, gain the pinned condition, are in danger of suffocating, and are trapped within its body until they are no longer pinned.

Paralysis (Ex)

A gelatinous cube secretes an anesthetizing slime. A target hit by a cube’s melee or engulf attack must succeed on a DC 12 Fortitude save or be paralyzed for 3d6 rounds. The cube can automatically engulf a paralyzed opponent.

Transparent (Ex)

Due to its lack of coloration, a gelatinous cube is difficult to discern. A DC 15 Perception check is required to notice a motionless gelatinous cube. Any creature that fails to notice a gelatinous cube and walks into it is automatically engulfed.


Environment any underground
Organization solitary

Gelatinous cubes spend their existence mindlessly roaming dark caverns, swallowing up organic material such as plants, refuse, carrion, and even living creatures. Materials the cube cannot digest, such as metal and stone, can eventually fill up the creature’s mass with such detritus, and at times the creature may excrete some of this material out of its body. Often the possessions of past victims remain inside the gelatinous cube, leaving a ghostly impression of their material remains.

Gelatinous cubes are generally 10 feet to a side and weigh upward of 15,000 pounds, though subterranean explorers report larger specimens in deep caverns. In locations with plentiful sources of food, gelatinous cubes can exist for hundreds of years, if not thousands. However, if denied organic material for more than 6 months, a gelatinous cube begins shrinking. Eventually this stresses its walls and the creature leaks rapidly evaporating slimy liquid until its body collapses and disappears completely.

Section 15: Copyright Notice

Alien Bestiary (Starfinder) © 2018, Legendary Games; Lead Designer: Jason Nelson. Authors: Anthony Adam, Kate Baker, John Bennet, Eytan Bernstein, Robert Brookes, Russ Brown, Duan Byrd, Jeff Dahl, Robyn Fields, Joel Flank, Matt Goodall, Robert J. Grady, Jim Groves, Steven T. Helt, Thurston Hillman, Tim Hitchcock, Nick Hite, Daniel Hunt, Mike Kimmel Marshall, Isabelle Lee, Jeff Lee, Lyz Liddell, Jason Nelson, Richard Pett, Tom Phillips, Alistair J. Rigg, Alex Riggs, Wendall Roy, Mike Shel, Neil Spicer, Todd Stewart, Russ Taylor, Rachel Ventura, Mike Welham, George Loki Williams, Scott Young.