Head and body length is about 300 mm and tail length is about 64 mm. The overall coloration is blackish brown.
Most individuals have three movable bands, but some have only two bands and others have four.
These are the only armadillos that can completely enclose themselves by rolling into a sphere. The second, third, and fourth toes of the hind foot are grown together, with nails almost like hoofs, while the first and fifth toes are slightly separated from the others and have normal claws. The short, thick tail, with prominent tubercles, is almost inflexible. T. tricinctus has five claws on the forefoot, but T. matacus has only four. All other armadillos have diploid numbers from 50 to 64.