Vedaranyam legend

Vedaranyam (Thirumarikkadu in tamil), situated in the coast at the lower right end of the cauvery delta, is one of the five temples where Muchukunda installed the Sphatika lingam he brought from heaven. It is placed in the iron chest secured by three huge locks.

Once, after the Archakas went home after Puja, the Deepam was about to go out. The Lord told Parvati that anybody who would kindle the flame of the Deepam and make it brighter would become the lord of the three worlds. A rat approached it and, with the idea of drinking the ghee in the Deepa, dragged the wick with its mouth as a result of which the Deepa was rekindled. Parvati asked Siva to keep his word. The Lord blessed the rat to be born as son to King Virochana. This child of Virochana was Mahabali who became Lord of the three worlds. It is therefore believed that the people who light deepams in this shrine of the Lord of Vedavana attain unique fame and supremacy.

Courtesy: http://www.hindubooks.org/temples/tamilnadu/vedaranyam/page9.htm