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.