Alchemy and Generating Lifeforce —Global Temples Made in the Shape of Lingams: Shaivite Bull Cult Part II
One form associated with the Bull Son of the Bull Cult was the Shiva Lingam, the sacred symbol that unites the phallus, the universal symbol of the male principle, with the ovum, the universal symbol of the female principle. The union of this polarity generates abundant life, which in many parts of the world was personified as the Green Man or Bull Son.
Source: ancient-origins.net