Astrophysicist Carl Sagan considered the possibility that ancient humans may have recorded visitations from extraterrestrials. One account from ancient Sumer, of the fish-like creature Oannes, “deserves more careful study,” he wrote.

Numerous ancient writers tell of a creature named Oannes, rising from a part of the Persian Gulf that bordered Babylonia, whose “whole body… was like that of a fish; and had under a fish’s head another head, and also feet below, similar to those of a man, subjoined to the fish’s tail.” According to the legend, Oannes bestowed upon the early Sumerians “insight into letters, and sciences, and every kind of art. He taught them to construct houses, to found temples, to compile laws, and explained to them the principles of geometrical knowledge.”

Other creatures in the likeness of Oannes are referenced in other ancient accounts, returning to check up on the Sumerians. They are called Apkallu.

“Sumerian civilization is depicted by the descendants of the Sumerians themselves to be of non-human origin,” Sagan commented. “A succession of strange creatures appears over the course of several generations. Their only apparent purpose is to instruct mankind. Each knows of the mission and accomplishments of his predecessors.”

Notably, the Apkallu are never described as gods.