https://en.wikipedia.org/wiki/Haruspex

In the religion of ancient Rome, a haruspex was a person trained to practise a form of divination called haruspicy, the inspection of the entrails of sacrificed animals, especially the livers of sacrificed sheep and poultry. Various ancient cultures of the Near East, such as the Babylonians, also read omens specifically from the liver, a practice also known by the Greek term hepatoscopy (also hepatomancy).

I've heard of the practice, but TIL the proper name for it.