Final answer:
Beavers possess a double/split toenail on their hind feet, which is important for grooming and maintaining their waterproof fur.
Step-by-step explanation:
Beavers have a double/split toenail on their hind feet. This specialized claw is used for grooming their fur, removing parasites, and working with construction materials when building dams and lodges. The second, or split, part of the toenail is a grooming claw that helps beavers maintain their waterproof fur, which is essential for their aquatic lifestyle.