The Shine Tower is a large monument found in Gelato Beach in Super Mario Sunshine. It houses the egg of the legendary Sand Bird. On the top of the tower is a globe-like device that gathers sunlight and directs it at the egg. Three large mirrors placed at various positions around the Shine Tower reflect the sun's rays onto the globe and help to incubate the giant egg.
In Episode 2 of Gelato Beach, Wiggler is found asleep on top of the tower, and many Plungelos are seen upsetting the balance of the three mirrors around the tower, all of which is collectively disturbing the delicate life cycle of the still unborn Sand Bird. Therefore, Mario must spray the Plungelos to the edges of each of the three mirrors and then Ground Pound them to restore their balance. Each time a mirror's balance has been fixed, the globe on top of the Shine Tower will glow brighter. When all three mirrors have been restored to their previous state, the globe will glow extremely bright, Wiggler will fall off of the tower, and a Shine Sprite will appear.
In Episode 4 of Gelato Beach, the Sand Bird is finally born. Mario must use a trampoline to bounce into the broken egg in the Shine Tower via a large hole in the side (presumably made by the Sand Bird), which will transport him onto a cloud near the flying Sand Bird when entered. From this point on, steel bars block the large gaping hole in the side of the Shine Tower, and it can no longer be entered.