The gelatinous cube is an original invention of Gary Gygax, rather than being inspired by outside sources and adapted to the roleplaying setting, as were many mythological monsters such as the minotaur and dryad, all of which appeared in the 1974 Monsters & Treasure book of the original boxed set.

Where are gelatinous cubes found?

The gelatinous cube is a subterranean creatures found in the dungeons of early Sosaria in Ultima I.

How is a gelatinous cube made?

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.