The skin of a worm allows it to move and change shape by having fibers wound in a cross-helical form around and along its body.

References

"The skin of a worm is a cylinder comprised of fibers wound in a cross-helical form around and along the worm's body. By contracting the muscles in the body wall and increasing its internal pressure, the worm is able to change shape, with the fibers in the skin allowing the worm to go from short and fat to long and thin." (Courtesy of the Biomimicry Guild)

Living System/s