Ayam Cemani is a breed of chicken/fowl which is black all through its body( both inside and outside the body). Etymologically, Ayam means "chicken" in the Indonesian language while cemani (originally a Javanese word) means "thoroughly black" (down to the bones).

Ayam Cemani is an uncommon and relatively modern breed of chicken from the island of Java, Indonesia. 

They have a dominant gene that causes hyperpigmentation (fibromelanosis), making the chicken mostly black, including feathers, beak, and internal organs. They are one of the most expensive breeds

Their beaks, tongues, combs, and wattles appear black, and even their meat, eggs, bones, and organs are black or gray. Their blood is normally colored. verification needed.

Photo credit: WIKIPEDIA

Source: WIKIPEDIA