There body form starts all small and gets more tiefling like form when the stronger they get (AKA Leveling up)
Gooplings are slime like creatures that was created by scientists. They have large black eyes, 4 figures, stubby feet, pointy ears, long pointy tail, white hair, and reddish slimy skin. Some comes with horns while some do not, this depends on where they were raised with tiefling or not.

They are capable to slide through tiny spaces/cracks, see completely in the dark, Mimic other species voice, and shift there body into any weapon they have used/studied. They can also eat anything that is hot, coal/charcoal food being there favorite.

You can only speak a small bit of Common language but is able to speak one language fluently, this can depend on where they live/raised.

Mostly commonly, Gooplings are in red skin with white hair but they can come in any color skin while the hair is always white and the eyes are always black. Colors of skin/slime being blue, pinkish purple, green, white, and black being the rarest. Each color represent different elements. Strength(red), Water(blue), Nature(green), Magic(pinkish purple), Wind(white), and Death/Dark(black)