Moles are small cylindrical
mammals adapted to a subterranean lifestyle. They have velvety fur; tiny or invisible ears and eyes; and short, powerful limbs with large paws oriented for digging.
The term is especially and most properly used for the true moles, those of the Talpidae family in the order Soricomorpha found in most parts of North America, Asia, and Europe. It also refers to other completely unrelated mammals of
Australia and southern Africa which have also evolved the mole body plan; while it is not commonly used for some talpids, such as desmans and shrew-moles, which do not fit the common definition of “mole” as well.
Moles have polydactyl hands; each hand has an extra thumb (also known as a prepollex) next to the regular thumb. While the mole's other digits have multiple joints, the prepollex has a single, sickle-shaped bone which develops later and differently than the other fingers during embryogenesis from a transformed sesamoid bone in the wrist. This supernumerary digit is species-specific as it is not present in shrews, the mole's closest relative. Androgenic steroids are known to affect the growth and formation of bones and there is a possible connection between this species-specific trait and the "male" genital apparatus in female moles in many mole species (gonads with testicular and ovary tissues).