Prayer Wheels were used to open the Seraph Chamber in the Barkhang Monastery in Tibet. They were scattered throughout the monastery.
In 1997, Lara Croft found them all and placed them to open the Seraph Chamber. She then placed the Seraph and opened the Catacombs of the Talion.
Prayer Wheels are collectible in Tomb Raider: Legend.
In Lara Croft: Relic Run, Prayer Wheel is the first relics in Mountain Pass level, worth 25 Coins. The relic can be obtained after finding 7 clues.
Prayer Wheel from Relic Run