Four sacred statues were hidden in the Gungan Caves on the planet Naboo. They held religious importance to the Gungans, a people of aquatic sentients.
Sometime after 32 BBY, Grand Master of the Jedi Order Yoda sent a young Jedi recruit on a mission to recover the statues. With the help the jewel keys he had found in the cave system, the youngling successfully unlocked the doors protecting the statues.
According to Daniel Wallace, the cancelled book The Essential Guide to Episode I was to explain the origin of the statues. One of its entry would have explained that the Gungan trickster god Nododo could "only appear in physical form as an opee sea killer, a kaadu, a peko peko, or a shaak." This would have conformed to the tenets of Gungan pantheism.