James P. Allen says that coexisting notions of one god and many gods would fit well with the "multiplicity of approaches" in Egyptian thought, as well as with the henotheistic practice of ordinary worshippers. He says that the Egyptians may have recognized the unity of the divine by "identifying their uniform notion of 'god' with a particular god, depending on the particular situation." Egyptian writings describe the gods' bodies in detail. They are made of precious materials; their flesh is gold, their bones are silver, and their hair is lapis lazuli. They give off a scent that the Egyptians likened to the incense used in rituals. Some texts give precise descriptions of particular deities, including their height and eye color. Yet these characteristics are not fixed; in myths, gods change their appearances to suit their own purposes. Egyptian texts often refer to deities' true, underlying forms as "mysterious". The Egyptians' visual representations of their gods are therefore not literal. They symbolize specific aspects of each deity's character, functioning much like the ideograms in hieroglyphic writing. For this reason, the funerary god Anubis is commonly shown in Egyptian art as a dog or jackal, a creature whose scavenging habits threaten the preservation of buried mummies, in an effort to counter this threat and employ it for protection. His black coloring alludes to the color of mummified flesh and to the fertile black soil that Egyptians saw as a symbol of resurrection. Most deities were depicted in several ways. Hathor could be a cow, cobra, lioness, or a woman with bovine horns or ears. By depicting a given god in different ways, the Egyptians expressed different aspects of its essential nature. The gods are depicted in a finite number of these symbolic forms, so they can often be distinguished from one another by their iconographies. These forms include men and women (anthropomorphism), animals (zoomorphism), and, more rarely, inanimate objects. Combinations of forms, such as deities with human bodies and animal heads, are common. New forms and increasingly complex combinations arose in the course of history, with the most surreal forms often found among the demons of the underworld. Some gods can only be distinguished from others if they are labeled in writing, as with Isis and Hathor. Because of the close connection between these goddesses, they could both wear the cow-horn headdress that was originally Hathor's alone. Certain features of divine images are more useful than others in determining a god's identity.