See study by K. Mellanby (1973).
Pigmented flat or fleshy skin mark, made up mostly of cells that produce melanin, which gives moles their light to dark brown or black colour and, in the dermis, a bluish cast. Thicker moles also contain nerve elements and connective tissue. Moles often begin in childhood, usually as flat spots between the dermis and epidermis. Those that remain there are more likely to become malignant. Most move into the dermis and become slightly raised. In children, moles may undergo changes resembling cancer but are benign. Malignant melanoma can begin in moles but almost never before puberty. During pregnancy, moles may enlarge and new ones may appear. Moles sometimes disappear with age. The term nevus refers to a congenital skin mark, whereas a mole may develop after birth. Epidermal nevi are usually the same colour as the surrounding skin.
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The eyes of moles and of some burrowing rodents are rudimentary in size, and in some cases are quite covered by skin and fur. This state of the eyes is probably due to gradual reduction from disuse, but aided perhaps by natural selection. In South America, a burrowing rodent, the tuco-tuco, or Ctenomys, is even more subterranean in its habits than the mole; and I was assured by a Spaniard, who had often caught them, that they were frequently blind. One which I kept alive was certainly in this condition, the cause, as appeared on dissection, having been inflammation of the nictitating membrane. As frequent inflammation of the eyes must be injurious to any animal, and as eyes are certainly not necessary to animals having subterranean habits, a reduction in their size, with the adhesion of the eyelids and growth of fur over them, might in such case be an advantage; and if so, natural selection would aid the effects of disuse. (Charles Darwin, The Origin of Species, The Origin of Species/Chapter V)
Moles burrow in lawns, raising molehills, and killing the lawn, for which they are sometimes considered pests. They can undermine plant roots, indirectly causing damage or death. Contrary to popular belief, moles do not eat plant roots.
Other common remedies for moles include cat litter and blood meal, to repel the mole, or flooding or smoking its burrow. There are also devices sold to trap the mole in its burrow, when one sees the "mole hill" moving and therefore knows where the animal is, and then stabbing it. Humane traps which capture the mole alive so that it may be transported elsewhere are also options.
Several groups of animals have a similar burrowing lifestyle, and some have developed close physical similarities with moles, forming good examples of convergent evolution.
Mole-like mammals are found in the family Chrysochloridae (the golden moles) and the family Notoryctidae (the marsupial moles). These are not related to true moles, but like moles they live underground and are insectivorous.
Mole-crickets are large burrowing insects which have strong digging forelimbs remarkably like those of moles.