Left: Armadillo Genus Alterum Clusii - "Armadillo, alternate genus" Right: Armadillo siue Aiatochtli - "Armadillo or Gourd Rabbit [from Nahuatl language]"
All genus of armadillo have armored scutes that protect them from predators when they roll up, but the hardness and organization of those scutes varies. Because of this armor, the animals tend to be fairly slow. The denseness means that they're also not naturally buoyant - however, the armadillo family has a counter for this! They inhale lots of air and expand their abdomen to twice the natural size, as well as being able to hold their breath for several minutes.
Ground armadillo has the dubious honor of being the only syphilis "cure" that you can contract Mycobacterium leprae from while preparing it. While I doubt Southerners are trying to cure syphilis with the armadillos they contact, it's worth noting that over 70% of the leprosy cases in the Southern United States in the past two decades are thought to have armadillo-based origins.
A Description of the Nature of Four-Footed Beasts; With Their Figures Engraven in Brass. Joannes Jonstonus, 1655.