Why do armadillo shells have movable bands?

Armadillo shells feature movable bands to provide the animal with flexibility and protection. These bony segments are covered in tough scales and overlap one another, allowing the armor to expand and contract like an accordion.12

This structural design is essential for the armadillo's survival, as it enables the animal to move with greater ease while remaining encased in its protective carapace. For instance, some species, such as the three-banded armadillo, utilize this flexibility to roll into a solid ball to protect their vulnerable underparts when threatened. Other species may use these bands to flex their back plates and wedge themselves firmly into burrows, making them difficult for predators to extract.1