Minor Alien Characters are non-Gem aliens that have appeared, but have no significant recurring role as of yet.
Jungle Moon Inhabitants
The "Arthropod Alien" is a species resembling a horned arthropod which inhabits the Jungle Moon.
They are dark-blue colored and have 4 eyes. A large horn extends upwards from the end of their beak-like rostrum, somewhat like a rhinoceros. When decapitated, they can sprout a new set of soft limbs from their head to escape.
They have a turquoise blue colored, blob-like body, pink or yellowish beaks, and have a single pair of limbs. Some are extremely small, while others are much larger than Stevonnie. They are able to roll into a rounder shape in order to travel on land. The larger ones are also able to fly by opening their body up into a cup shape, and closing to pump out air and rise, and have curved claws.
The "Ungulate Alien" is a species which somewhat resembles Earth's ungulates that inhabits the Jungle Moon.
They have a turquoise blue color with pale yellow stripes, a tall hump on their back, a pinkish beak, and feet like the cloven hooves of an even-toed ungulate. They are able to shoot water out from the sides of their beak.
These aliens have appeared in the show, but where they came from has no significance.
Thing (Rainbow Caterpillar)
"Thing" is a worm-like alien species from a Kyanite colony. As said in Steven's dream of his mother's memories in "Change Your Mind", Pink Diamond once let a bunch of them loose in Homeworld's ballroom, and was thrown into the Prison Tower as a result.
They have a rainbow-colored body split in a total of seven segments. They have dark blue eyes with yellow sclera, a short nose, and a mouth fixed into a smile. They also have six legs, two on the yellow segment, two on the green segment, and two on the dark blue segment. The last segment appears to be glowing, akin to a firefly's. They seem to be mischievous, as they chase Pearls through the halls, and one managed to hide in Blue Diamond's hair.