Glyptodont are covered by a protective shell composed of more than 1,000 2.5 cm-thick bony plates, called osteoderms or scutes. Each species of glyptodon has its own unique osteoderm pattern and shell type. With this protection they were armored like turtles. Unlike most turtles, glyptodons can not withdraw their heads, but instead has a bony cap on the top of their skull. Even the tail of Glyptodon has a ring of bones for protection. Such a massive shell needs considerable support, evidenced by features such as fused vertebrae, short but massive limbs, and a broad shoulder girdle.
The nasal passage is reduced with heavy muscle attachments for some unknown purpose. Some naturalists have speculated that the muscle attachments are for a proboscis, or trunk, much like that of a tapir or elephant. Most animals with a trunk, however, have nasal bones receding back on the skull, and glyptodonts do not have this feature. The lower jaws are very deep and helped support massive chewing muscles to help chew the coarse fibrous plants that can be found along river and lake banks.
Glyptodonts grow very large. One of the largest was Glyptodon, which was captured in Borea in 1839 was 5 feet (1.5 meters) tall and 10 feet (3.3 meters) long. These creatures are relatively benign, and will not attack, even when rushed by predators, unless they receive a substantial amount of pain or are cornered into an enclosed space. Some settlers of Borea have even tamed the creatures as pets.