The naked mole-rat (Heterocephalus glaber), also known as the sand puppy,[4] is a burrowing rodent native to parts of East Africa. It is closely related to the blesmols and is the only species in the genus Heterocephalus of the family Heterocephalidae.[5][failed verification] The naked mole-rat and the Damaraland mole-rat (Fukomys damarensis)[6][7] are the only known eusocial mammals, the highest classification of sociality. It has a highly unusual set of physical traits that allow it to thrive in a harsh underground environment and is the only mammalian thermoconformer, almost entirely ectothermic (cold-blooded) in how it regulates body temperature.[8] The naked mole-rat lacks pain sensitivity in its skin, and has very low metabolic and respiratory rates. While formerly considered to belong to the same family as other African mole-rats, Bathyergidae, more recent investigation places it in a separate family, Heterocephalidae.[9][10][11] The naked mole-rat is also remarkable for its longevity and its resistance to cancer and oxygen deprivation.