TAMIL NADU, INDIA, March 5, 2016 (The News Minute): About 25 miles from the famous Chettinad region of Tamil Nadu, is a little known temple dedicated to a formless God, built by Manikkavasakar, an iconic 9th century Tamil poet and saint. The temple, called Avudaiyarkovil, stands in a small town in the Pudukkottai district. The town was originally called Perundhurai, but is now called Avudaiyarkovil after the temple.
Manikkavasakar was one of the Naalvars, regarded as the four greatest Tamil Shaivite saints who lived between the 7th and 9th centuries. While the temple was originally built by Manikkavasakar in the 9th century, additions and modifications were made over time, and most of the current structure is believed to date back to the 15th century.
What sets this temple apart from other Shiva temples is that the main Deity here, is formless. Shiva-lingams are usually placed on a base called a peeta, but here, the sanctum has only a metal peeta, and no lingam on it. The version of Shiva worshipped here is called Atmanatha, which means the Lord of the Soul. Another departure from the norm here is that there is no Nandi (the bull that is believed to be Lord Shiva’s vehicle). The offering to this formless deity is just the steam that rises up when hot rice mixed with slices of dried bitter gourd is spread on a stone slab.
Photos at “source”.