From Halopedia, the Halo wiki
A ghost scorpion is a species of arachnid native to Gao, a human Outer Colony. Ghost scorpions are a troglobitic species; they are blind, albino creatures that live in the depths of the Montero Cave System near the Forerunner Covert Support Base 4276. Ghost scorpions are one of the handful of species that live near the support base, sharing their environment with fellow troglobites such as the no-shell snails and chirping spiders. Some ghost scorpions were nurtured by Lifeworker Huragok Roams Alone near the Covert Support Base.