Yoga nidra of Mahavishnu

When Mahavishnu is meditating in the 'Yoga Nidra' [योग निद्रा], appearing outwardly to be resting on the bed of Adisesha who is the Kundalini snake, He is merged with Paramatma, in the Parameswara form, and is actually engrossed in this Ajapa exercise.  The movement of Parameswara at that moment, which is in sync with the movement of His (Vishnu's) breathing, is Tyagaraja's Ajapa dance or Hamsa dance.

If this – Siva dancing on the heart of Vishnu – is depicted as a deity, the ignorant, who form the majority of people, would think erroneously.  It could be considered to be similar to Nataraja dancing on Muyalagan, or Kali dancing on the chest of Paramasiva, etc., which are perceived as annihilation of the enemy!  Siva and Vishnu, who go as one without any differences, could be thought of as worst enemies!

This is why, everything is covered fully and only the face is made visible in the deity of Tyagaraja, in Tiruvarur.