The mellomeura (/mɛləˈmjʊːɹə/) is a gooey, petite enemy whose translucent head stands pale against its already light-colored body. Its surface appears skinless but fleshy, and at high enough resolutions, the thin lines of veins can seem to be seen beneath its skin.

Physical attacks cause the mellomeura to shudder, and then break apart into white goo (the "mello_goo.SPRITE" coming into use here, and only here, deforming upwards and across in some show of animation). Special attacks, however, turn the mellomeura translucent for several seconds, with no other "impact" animation. Regardless of means, when the stranger is killed, its shimmering model fades to white as it collapses and congeals, virulent and shapeless, before its corpse disappears¹ from the world.

Developer notes state:

The mellomeura's audio is limited to a handful of sniffles and whimpers.

The mellomeura is not a common enemy, with many players missing it entirely. It is most often encountered in the Train Graveyard, where the high experience points it yields when killed make it sought-out by those looking to level up quickly early in the game. It can also be fought in the Sector 6 slums, as well as (rarely) in the Sector 1 reactor.

It appears either by itself, or with a Hell House (when found in Sector 6).

As with almost all of the game's enemies, the mellomeura is given little backstory. Whether it is a twisted genetic experiment, supernatural phenomenon, or wild animal cannot be said.

In its idle posture, the mellomeura seems alternatively scrutinizing, and bashful towards the party. It is immune to many status effects, and bears some of the lowest stats in the game. Despite its obvious weakness, however, the mellomeura is one of the most dangerous enemies in the game. This is due to the danger of "everybody's touch", a special attack which it becomes more likely to use as the battle goes on.

Developer notes state:

The party member presents with a range of specific effects, including, but not limited to:

Attacking of the self twice each tenth turn.
Two-turn loss of 100% of defense.
"Double poisoning".
Character's face turns pale red.
Jerking animations and loss of 10% of hit points each turn.

The number of symptoms increases as time goes on. Once the "everybody's touch" condition is present, it can never be cured. Though there are those players who chose to contract the condition as a challenge condition, any further action (especially saving the game) after contracting the virus leads only to an inevitable game-over scenario.

As of yet, the longest recorded length of an "everybody's touch" run is fifty-one minutes of battle time. The player can, however, constantly flee from non-boss battles to advance the story and avoid their playthrough's inevitable end. Doing so yields only one difference; when infiltrating the laboratory chambers in the Shinra tower, a message scrawled on the wall in blood reads, "they kill the ones who pull our strings." Otherwise, there are no other known changes to the non-battle components of the game.

Should a party character faint during the battle, the mellomeura attempts to use its "vile funeral" attack.

Developer notes state:

Although the "sensitive" and "stranger" elements seem to have been dropped from the game entirely, the effect is implemented as described. The "vile funeral" causes a sputtering and morphing effect, within which the body disappears.

The party slot goes blank, and with no corpse to leave behind, there is neither a phoenix down nor life spell that can revive the "consumed" party member. Should the player wish to use that character again, they must either reload from an earlier save point, or start the game over.

The mellomeura's inclusion as an enemy remains confusing, to say nothing of the unexplored "sensitive" and "stranger" concepts. Regardless, the level of detail and lack of glitches or bugs makes the mellomeura stand out even amongst other "concealed content" from both this and other games.

Though the mellomeura received "official" implementation only in the "dummy" release of the game, its code was discovered (and could be patched in) as early as one hundred and forty years after the game's original release.