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When Walt, Larry, and Igner infiltrate Planet Express to find the Anti-Backwards Crystal, they kidnapped Nibbler and imprisoned him with the rest of the Nibblonian population in Mom’s Dark Matter Mine. His hellish imprisonment of being force-fed chickens and prune juice, while having his excrement harvested for fuel, was ended when the dark matter was made unusable as fuel, only to be utilized by Professor Hubert J. Farnsworth’s brilliant replacement for the starship fuel: Nibbler Power.

Nibbler is a biped, about a foot tall, with black fur, long arms, stubby legs, as well as a proportionally large head. He has two large eyes embedded in his skull and a small third eye on the end of a stalk that protrudes from the top of his head and only one nostril on his nose. He has large fangs and a surprisingly wide mouth, making him capable of eating any creature regardless of its size. He wears yellow shoes, a white diaper, and a red cape. He excretes small but super-dense round pellets of dark matter, though he’s light enough for humans to easily pick up. These traits are assumed to be standard for all Nibblonians.