Vanniyappar Temple, Alwarkurichi – Legends
During Dwapara Yuga, the Saptharishis were performing a Yagna to protect people from being killed by the Pralaya. Fearing his power would be lost, Agni did not help the burning of the sacrificial fire. Angered by this, the Rishis cursed Agni to lose his heat, light and energy. Agni was shocked and wanted to escape from the Sapa Hathi. So he took the form of a fish and hid in the Herambayar Theertham near the Patha River. Since Agni went missing, the Saptharishis asked his three elder brothers to take the Havi (offering) of the Yagna to Lord Shiva.
The three brothers, not having the strength to carry the Havi, perished. In the meantime, the Sapa Hathi came looking for Agni, found him hiding in the Herambayar Theertham, and caught him. Agni lost his heat, light and energy. When Sage Sudama came to the Theertham for a holy bath, Agni knelt at his feet and asked for a way out of his misery. The Sage asked him to install a Shiva Linga there and worship him to be rid of his curse.
Agni did as advised and soon regained his strength and vigor through the grace of the Lord. He also helped the Saptharishis complete the Yagna by carrying the Havi all by himself. Since Agni installed the Shiva Linga here, the place came to be known as Agni Theertham.
Agni named the river Rama Nadhi as he helped to prove the chastity of Mother Sita.
According to the Tambiraparani Mahatmiyam, worshipping here on Solar and Lunar Eclipse days as well as Tamil New Year, New Moon and Full moon days and Ashtami will help one see the vision of the Lord in the form of Light. It will also help them gain all kinds of wealth.