Gelatinous cube

A gelatinous cube' is a transparent ooze composed of mindless, gelatinous matter in the shape of a cube.

The average gelatinous cube measured 10 feet to a side and weighed as much as 15,000 pounds. The creature is completely transparent, with only a glint of its shiny form in the light being the last thing an adventurer ever saw.

Abilities

 * Senses: Blindsight.
 * Languages: None.
 * Condition Immunities: The blinded, charmed, deafened, exhaustion, frightened and prone condition.
 * Attacks:
 * Pseudopod: The gelatinous cube can make a melee attack causing acid damage.
 * Engulf: The gelatinous cube can enter a Large or smaller creatures' spaces to cause damage and suffocate them.

Known Gelatinous Cubes
The Mighty Nein encounters and defeat a gelatinous cube in the Abandoned Research Facility.