The Rabbit, called the Hare in many older sources, is paired with mao, the fourth earthly branch, whose double-hour runs from five to seven in the morning, the hour of sunrise, and whose phase is wood. In the Vietnamese version of the cycle this position is held by the Cat rather than the rabbit, a substitution usually explained by the closeness of the branch name mao to the Vietnamese word for cat, and it is a useful reminder that the twelve animals are a regional convention rather than a fixed universal. The rabbit is a lunar animal in Chinese tradition: the Jade Rabbit is seen in the markings of the full moon, pounding the elixir of immortality in a mortar for the moon goddess Chang-e, and moon cakes and rabbit imagery belong to the Mid-Autumn Festival.
The rabbit-in-the-moon image is not unique to China: Mesoamerican traditions, including the Aztec, independently read the same lunar markings as a rabbit, a striking case of two unconnected cultures arriving at the same pareidolic reading of the Moon's surface from opposite sides of the world with no plausible route of contact. Within the Chinese tradition itself the Jade Rabbit's task of pounding the elixir of immortality is sometimes conflated in later popular retellings with an entirely separate pounding-mortar image belonging to the medicine goddess tradition, a blending folklorists treat as a later popular layering onto the older, simpler Chang-e myth rather than part of its original form.