The aye-aye is a long-fingered lemur, a strepsirrhine primate native to Madagascar with rodent-like teeth that perpetually grow and a special thin middle finger that they can use to catch grubs and larvae out of tree trunks.
Aye-aye
Skeleton
Closeup of the hand showing the elongated digits and the thinner third digit
An aye-aye foraging, c. 1863, Joseph Wolf
Lemurs are wet-nosed primates of the superfamily Lemuroidea, divided into 8 families and consisting of 15 genera and around 100 existing species. They are endemic to the island of Madagascar. Most existing lemurs are small, have a pointed snout, large eyes, and a long tail. They chiefly live in trees and are active at night.
Lemur
A life restoration of Babakotia radofilai, a sloth lemur that became extinct less than two thousand years ago
Close-up of a ruffed lemur's foot, showing the toilet-claw on the second toe and nails on all other toes
A six-tooth version of the strepsirrhine toothcomb in a ring-tailed lemur, with canine-like premolars behind it