Behold, the strangest six-fingered primates on the planet (also the only ones) - The Washington Post

Aye-aye hands have small "psuedo-thumbs," fingerprints and all, in addition to the five fingers all primates have.
https://www.washingtonpost.com/science/2019/10/21/these-bizarre-lemurs-are-only-known-primates-with-six-fingered-hands/