From a Wikipedia research spiral:

Armadillos possess the unique reproductive trait of monozygotic polyembryony, meaning their offspring are genetically identical due to the division of a single fertilized egg into four matching embryos. This development of identical quadruplets has been utilized as a tool for genetic research. It is possible that the monozygotic polyembryony was an adaptation to accommodate for the female’s inability to carry more than one egg during this pre-implantation stage. Delaying the implantation further has no effect on the number of offspring produced.

Armadillos are also carriers of leprosy, as I learned in my Infectious Diseases course in undergrad.  And they have the now unfortunate fear response of jumping, which means they often kill themselves on car bumpers when the vehicle would have otherwise safely passed over the animal.  They are a fascinating creature.