A large work machine built before the One Year War, it is the progenitor of mobile suit. It has a cylindrical body with a large monoeye and four arms, two above and two below its protruding shoulders. It has no legs, and its movement is done by hovering. Although it is designed for work, its power output is comparable to that of a combat MS, and one of its arms has a multi-armed firearm.

An unknown number of Catl were produced before the One Year War and fielded in space for colony construction. One Catl unit still existed at the Moon Moon colony in U.C 0088, where it was worshipped as a sacred object by the Light Tribe. Mondo Agake and Rasara Moon reactivated the ancient mobile worker and used it in battle against several of Neo Zeon's AMX-003 Gaza-C units. Surprisingly, the aging mobile worker proved to be formidable in combat and fought off the enemy mobile suits despite being built primarily for construction.