Origin story
The serpents Ananta, Vasuki and Takshaka belong to the race of Nagas who dwell in Patala and serve as the couch of Vishnu. In Kerala the Naga deities are believed to guard ancestral land, and offerings are made to Nagaraja and Naga Yakshi in the sacred groves.
The cobra hood, the gem in the hood and the coiled form represent hidden power, fertility and the kundalini energy. Serpent worship is among the oldest rites of the region, and the sarpa kavus preserve it as a living tradition protected by the family and the village.
Source: Wikipedia: Nagaraja — https://en.wikipedia.org/wiki/Nagaraja
