Lord Viṣṇu has several aspects of manifestation. The one depicting him as reclining on the coils of serpent Śeṣa or Ananta (as bed) is called ‘Śeṣaśayana’ or ‘Anantaśayana.’
The śayana-images (images showing Viṣṇu, in the reclining posture) are of four types: yogaśayana, bhogaśayana, vīraśayana and ābhicārikaśayana. The first shows him with two arms and in a meditative mood, with half—closed eyes. Instead of Śrī and Bhū, the two consorts, the sages Bhṛgu and Mārkaṇḍeya are shown. Brahmā is shown seated on the lotus emerging from his navel. In the second type there are four arms and the icon is fully bedecked with ornaments. Śrī and Bhū are also shown along with the sages Bhṛgu and Mārkaṇḍeya. Brahmā and Śiva are shown on the rear wall. In the third type, he is holding śaṅkha (conch) and cakra (discus) in two of the four hands. The demons Madhu and Kaiṭabha are shown at his feet, trying to attack him. In the last type, he is shown with an emaciated body, scanty clothing and with no attendants. This image is usually set up outside the town or village.
These four images are respectively worshipped by those seeking spiritual welfare, worldly enjoyments, strength and destruction of enemies.
Trivandrum, capital city of Kerala state, was formerly known as Tiru-Ananta-puram or Anantaśayana since it has a reputed temple dedicated to Ananta-śayana, also called Padmanābha. It is one of the well-known shrines dedicated to Viṣṇu and was probably built during the early medieval era. The image is made of stucco and hence no abhiṣeka (ceremonial bathing) is done to it.
The main difference between the Raṅganātha icon (which is also a śayana—image) and Anantaśayana is that the latter has Brahmā on the lotus rising from the navel whereas the former does not have it.