During their growing stages the Great Sandworms shed their segmented carapaces a number of times.The husks shed during the first 6 months of a Sandworm's life are reasonably flexible while those shed later are much tougher. The husks are collected by the desert tribes, which protect the Sandworms, and put to a variety uses.
The larval husks are ground up and used in a fertilizer mix to enrich the sandy soil the desert tribes grow their meagre crops in. Youngling husks, being slightly more flexible in nature and more easily shaped, are used to make anything from decorations and jewellery to plates and bowls. The husks shed during the second and third year of a Sandworm's life are much tougher and larger. These are used in the manufacture of armour and also used as a building material, being naturally insulating and abrasion resistant.
Due to the close relationship the tribes of the desert have with the Great Sandworms, the husks are easy to gather and oftimes they will help those Sandworms which are having difficulty escaping from their old husks. Sandworms nest close by desert settlements and remain close by during their growing years too, thus the tribes never have to travel far to collect this valuable resource.