What is "leyak"

In the folklore of Bali, the Leyak (in Indonesian, people called it 'Leak' (le-ak)—the Y is not written or spoken) is a mythological figure in the form of flying head with entrails ( heart, lung, liver, etc.) still attached. Leyak is said to fly trying to find a pregnant woman in order to suck her baby's blood or a newborn child. There are three legendary Leyak, two females and one male.