Polymorph (Ben 10)

Polymorph (a word meaning "many shapes") is a species of unicellular organisms from the molten planet of Viscosia.

Apperance
Polymorphs are gelatinous extraterrestrial blobs of slime that come in many colors including light green, red, blue, orange, mint green, purple, and grey.

The slime is normally in a humanoid shape with a pointed head, narrow eyes, and "spikes" on their shoulders. They can, however, turn into a shapeless mass such as a puddle or mimic the shape of something.

Technology
Polymorphs are equipped with small grey UFO-shaped devices called anti-gravity projectors that hover over their head, replicating the gravity of their home planet and allowing them to levitate and change shape.

Abilities
Polymorphs have strong digestive acids, which can be used as an offensive weapon, either by smothering something or releasing a sort of corrosive gas.

Polymorphs are almost invulnerable because even when their slime has been scattered all over the area, they can still recollect as long as their anti-gravity projector is still active.

Weaknesses
Outside of Viscosia's gravity, Polymorphs can only have its body function when it is united with its anti-gravity projector. This means that if the two are separated, the slime will go inert until recollected.

Omnitrix Transformation
The Omnitrix's Polymorph representative is named Goop, who first appeared in the Alien Force episode "The Gauntlet". Goop has appeared in almost every subsequent series except the reboot.

The Ben Tennyson of Dimension 23 has an equivalent of Goop named Muck-A-Muck, who was confirmed to exist in the Omniverse episode "It's a Mad, Mad, Mad Ben World: Part 1".

Goop has also been used by the Prime Timeline Vilgax and Albedo. According to Derrick J. Wyatt, Bad Ben, Mad Ben, Nega Ben, and Benzarro all have Goop available in their Omnitrixes.