Not very much is known about the Koorma Avatar and the number of Temples for Koorma Avatar (Tortoise), when Lord Vishnu bore the weight of the Meru Mountain while churning the Milky Ocean to beget Nectar.
During this process, Lord Shiva swallowed the poison which came out of this process.
The Tortoise Koorma, became uncontrollable an it had to be pacified by reminding that it was an Avatar of Vishnu.
Much as one would use a trained elephant to pacify an uncontrollable one, Lord Shiva took the Avatar of Koorma to pacify Vishnu.
The temple in Thiru Tandalai, near Vellore, Tamil Nadu has a Shiva Temple, where the Swayambu Lingam(self made) has the markings of tortoise skin.
Main Deity is Swayambu Lingam known as Arulmigu Neelneri nadhar and his consort known as Gyanambikai. Teertham is Omaga Teertham and Sthala Vruksham is Orilai Kuruntham.
The Moolavar is also known as Sthira Buddhi Easwarar, one who grants steadfastness of Mind.
This is a Parihara Sthala for the mentally disturbed.
As we go around the inner prakaram we see, Vinayakar, Arumugar, Soorya Chandran, Arivattaya Nayanar, Natarajar, Cochengat chozar and Siva Lingas worshiped by Vyagyapadhar and Patanjali muni.
The Deity is known as Neelneri Natahr in Tamil and is one of the 275 sthalas praised by the Nayanmars(Shiva Bhakthas)
The temple is 3 km form Thiruthuraipoondi and can also be reached from Vellore.
Sri Neeneri Nathar Temple, Thandalaicherry, Velur – 614 715. Tiruthuraipoondi taluk, Tiruvarur district.
+91- 98658 44677, Check the Phone number.
Temple Timings. 6.30 am to 12 and 4 30 pm to 830 pm.