Amorphous Shape resembles an unfolded Rubik's Cube, composed of many colorful contorted squares of light blue, light green, purple, pink and orange, several of which have eyes on them. It has a thin white aura and two long, tail-like protrusions, both of which hang off of the two purple colored squares on its body. The protrusions are tipped with glowing blue tufts.
Eons before the events of the series, Amorphous Shape indulged in criminal activities before being called together by Bill Cipher, along with 8 Ball, Hectorgon, Kryptos, Teeth, Paci-Fire, Keyhole, Pyronica, Lava Lamp Shaped Creature, and Xanthar.
In "Weirdmageddon Part 1", during the cold open, Bill introduces Amorphous Shape and the rest of his friends to the residents of Gravity Falls. Afterwards, on Main Street, Amorphous Shape and the other beings watch Bill turn Ford into a golden statue and taunt Dipper before burning the journals. Later in the episode, Amorphous Shape is seen playing "Spin the Person" and enjoying the "V.I.P." party Bill is having at the Fearamid until Time Baby and the Time Police crash the party. To the beings' delight, Bill vaporizes Time Baby and his squadron. The party then continues as Amorphous Shape and the other beings rejoice over Time Baby's presumed death.
In "Weirdmageddon 2: Escape From Reality", Amorphous Shape and the rest of Bill's minions attempt to leave Gravity Falls and spread their chaos worldwide, but are stopped by an invisible barrier around the town.
In "Weirdmageddon 3: Take Back The Falls", following Bill's defeat, it was sucked back into the Nightmare Realm along with its comrades.