Robot crawlers were built for surface operations on the low-gravity surface of the Toltan Moon. Their purpose was to benignly retrieve Toltan astronauts once they had achieved a moon landing. The vehicles were several stories tall and rode on six sets of wheel treads, two under the body of the vehicle and two each under pairs of wheeled armatures. The crawlers were capable of generating telepathic signals and paralysis beams to freeze their targets. The central body of the vehicle contained a number of coiled mechanical tentacles to grab and hold objects.
In the 14th century, a robot crawler on the surface of one Toltan Moon secured two Toltan astronauts with its coils, who were the lone survivors of their race. They were placed into suspended animation in the interior of the Toltan Moon.
In the 23rd century, the spacesuited James T. Kirk, Spock and Leonard McCoy were investigating the fate of the two astronauts by following 900-year-old robot crawler tracks. A crawler approached the landing party. It paralyzed them, grabbed them in its coils, and brought them within the underground complex of the Toltan Moon. It deposited them in large banks of suspended animation chambers beside the hibernating Toltan astronauts. Before they could be permanently suspended, Spock was able to call out through his communicator to transport the landing party and Toltans aboard the Enterprise. (TOS comic: "Called Home")
- Although the crawler did not make a cover appearance, its tire tracks were referred to in sample artwork on the back cover of The Newspaper Comics, Volume 1.