SAPTHA VIDANGA STHALAM
Thirunallar has claims to additional impartance as the Second of the seven Saptha Vidanga Sthalas. In other words, this sacred place enshrines a naturally formed Marakatha [emerald] linga known as Navagavidanga which is the second out of the seven images gifted the Indra to a Chola King by name.
Muchukunda returned to earth with the seven Thyagarajar moorthis and installed them at various places in his kingdom. The original one he kept at the temple at Thiruvarur, and the others at Thirunallar, Vedaranyam, Thiruvaimur, Thrirukaravasal, Thirukkuvalai and Nagapattinam. These seven temples are collectively known as Saptha Vidanga Sthalams. Vidanga means something that has not been chiseled out. These seven Thyagarajar moorthi are believed to be divine – not made by chisels.
The sanctum on the left side of Tyagaraja has the Marakathalinga kept in an iron safe. Abhishekas and pujas are offered to it five times a day.
It is computed that there are 17 Sivalingas in this sacred place includind Darbharanyeswara in the main shirne and those that the lords of the 8 cardinal points [Dik Palakas] has established and worshipped along with a sacred tank in each of the cardinal points to which they are respectively accredited.
The details of the Saptha Vidanga Sthalams:
Name of Thayagaraja
Vandu or Brahma Nadanam