The chull is a species of crustacean useful for labor intensive jobs, such as pulling bridges over the caverns of the Shattered Plains. There are differing breeds of chulls and they come in a variety of shapes and sizes.
Description
The carapace of a chull is red and it has thick legs with claws, plus a bulging shell like stone. It was said a chull's claws could snap a man's arm, however, the crustaceans are docile - particularly domesticated ones - and are not known to harm anyone.[1]
The shells are "lighter" than they appear and chulls are not hurt when their shells are cracked or shaped. Some people sand flat places on top of a chull to ride and many carts are hooked to fittings drilled directly into their shells.
Use
There are two major ways of directing a chull. The first is similar to the way in which one directs a horse, with complex leather workings, and the second involves tapping the antennae of a chull with a long pole to indicate direction.
Dalinar Kholin uses them to pull his bridges, rather than put the lives of bridgemen at risk.[2]