Like the god Geb, Aker was a personification of the earth. As such had a positive side as well as a (less stressed) negative one. He represented the feared realm of the dead in the dark earth, in which the travelling deceased could be hindered; but at the same time, more importantly, it was from Aker that the dead would arise into the light of the day, exactly like the sun god, who journeyed through the earth each night; for this Aker would also help the deceased by protecting him against the snakes that live in the earth. Because of these functions, amulets in the shape of Aker were often given to the deceased.
Usually Aker is depicted as a flat sign (the hieroglyph for earth), terminating at both ends in the front part of a lion (often with a human head, like a sphinx), although in the Old Kingdom he was usually depicted with only one head. Sometimes the solar bark is shown between the heads of Aker.