There are three moolavars on top of the hill (irundhaan, kidandhaan, nadandhaan - postures) and one moolvar at the foothill (ninraan).
Vaalmiki maharishi visited this temple & worshiped the Lords. Lord Ranganathar as Raama & Ranganayagi as Seetha Devi, Aadiseshan as Lakshmanan, Changu Chakram as Baratha Sahatugnan, Vishvaksenar as Sugreevan, Garudan as Hanuman gave him darshan.
When Thirumangaialwar visited this temple, the hil was surrounded by water & he had to wait for six months to get the darshan of the Lord & hence the name Thiruneermalai (neer - water). Th eplace where Thirumangaialwar stayed during his wait is still known as Thirumangai Alwarpuram.
Temple at the foothill
The moolavar is Neervannan, Neelamugilvannan seen in standing posture facing east.
Thaayaar - Animaamalar Mangai.
Temple at the top of the hill
Moolavar (Irundhaan) - Saantha Narasimhan seen in seated posture facing east.
Moolavar (Kidandhaan) - Ranganathan seen in reclining maanicka sayana posture facing south.
Thaayaar - Ranganayagi faing east.
Moolavar (Nadandhaan) - Tiruvikraman seen in standing posture facing east.
Theertham - Manikarniga Thdaakam - Sheera Pushkarini, Kaarunya Pushkarini, Siddha Pushkarini, Swarna Pushkarini.
Thirumangaialwar - 1078-87, 1115, 1521, 1554, 1660, 1765, 1848, 2069, 2673 (73), 2674 (130)
Boodathalwar - 2227.
Total of 20 Paasurams.