This is a pillar in Katchi Mandapam,  Arunachaleshwar Temple, Tiruvannamalai.

Siva is identified by battle axe and antelope (Mirga) in his upper right and left hands respectively. His lower hands are in Abhaya and Varada mudra.

What is interesting is, Siva is carried by a human (Nara) figure and Siva’s legs are supported by the human figure’s hands.  Never come across such a form of Siva.

Looked up my goto books Elements of Hindu Iconography by T A G Rao and Siva Parvati and Allied Images by D E Donaldson and could not find any similar figures or references to such form.

There is a possibility the figure below may represent Ravana and this form may be Ravanaanugraha Murti. However in such forms, Siva is portrayed along with Parvati as in Umamaheshwara, and Ravana is shown with ten heads.  Also in those forms, Ravana is seen lifting Mount Kailash rather than carrying Siva directly.

The relief sculpture above is closer to of Garuda Narayana rather than Ravanaanugraha Murti.

Only Kubera, when depicted as an Astadikpala, is known have human (Nara) as his vahana.

The Katchi Mandapam is dated to the thirteenth century.

The photo was taken by me (Oct 2017). Feel free to use the comments section or contact me.

13 Dec 2018: Found the picture below in the Facebook pages of Panneerselvam. The sculpture is from Ekambareshwar Temple, Kanchipuram. According to Padma, it represents Nandi, in human form, carrying Siva and Parvati.