The four great ages, just as the four sacred directions/winds/corners/legs. Sometimes this is symbolized by a tortoise holding the world (because tortoises are symbols of old age and long lives).
Though in many ancient cultures it is symbolized by a bull.
The great bull of heaven in zoroastrianism. The white buffalo of native Lakota, the bull of dharma and the yugas or the bull of egypt. Mostly this bull is symbol of the highest god osiris=apis; shiva=nandi; the great behemoth (behema=cattle) made by yahweh (yah=egyptian bull god), or tammuz/dumuzid the bull god. Why a bull then? Because the bull is a symbol of strength. The rage of the bull, the male estrogen/fertility of the bull, but often also depicted with the female cow and the milk, strengthening the young calf, becoming the next bull of the next cycle or age.
Often these bulls are depicted with water (like the water buffalo). Why? Well, not directly because of the milk, (although often the milky way is said to be a milk ocean) but because of the moon. As a crescent it is symbol of the horns of the bull and it controls the tides or the sea waters. Water is a sacred symbol. Without it life, plants, animals, sea creatures, nothing organic could exist. So the king over the earthly realm is the great rock god or moon and the king over the spirit is the great sun/fire god, sometimes the air god, since fire needs oxygen, or plasma being an active gas. Now this actually makes sense. Fire being the soul or spark (brain), driven by the air (lungs/heart). And water being the lower manifest (liquid, but not yet solid) making the material realm (solid)
In egyptian mythology this is depicted by the stone/egg of creation, from which osiris rises. We also see this as moses/moshe in the basket. We also get the meaning of water mem, for the mother and shin for fire and the father.
The sun/soul emanating/impregnating the moon/body, until it's full and then returns back to darkness and dies.
There it goes through four stages: birth/adolescence=spring; youth/adulthood=summer; old age=Autumn/fall and death=winter. So during this winter, the ice is holding back the waters for new spring, the first light of the new born/rising sun, (birthed out of the ground/mother earth) which has red color (just like the blood of the uterus during birth, or the also salty sea water turning into clouds and making it rain, starting a new lifecycle.