At some point, it was split into two pieces. One of these pieces was found and put into the Bikini Bottom Museum. The other one was found by SpongeBob and Patrick in Dave the Cave.
Role in series
SpongeBob and Patrick are trying to take photos of bubbles, but they keep popping. SpongeBob tries to make a bubble that will last all day but ends up making a bubble big enough to trap SpongeBob and Patrick in. They float around for a while until they end up in Dave the Cave. The bubble then pops.
According to "Atlantis SquarePantis," SpongeBob and Patrick find the missing half as soon as they enter the cave, it being the thing that pops the bubble. Patrick thinks it is a relic from SpongeBob's family and sticks it in SpongeBob and SpongeBob suggests that someone at the Bikini Bottom Museum might be able to figure out what it is.
According to SpongeBob's Atlantis SquarePantis, the bubble pops and they have to travel through several levels of a giant cave. On the last four, the missing half is split into pieces and SpongeBob and Patrick have to collect those pieces in order to make it a whole piece again. Once they do, the story is the same as Atlantis SquarePantis.
The two go to the Museum and run into Squidward who is practicing his painting skills by looking at a painting of King Neptune. Squidward thinks that the two have stolen the piece that is already in the museum. He is going to return it, but when he does, he finds out that it is the missing half. He then tells the tale of the lost city of Atlantis. Mr. Krabs and Sandy overhear the story. Sandy says that once the two pieces are connected the path to Atlantis will open. Squidward does this and a bus called, "The Sea Ship Atlantis" appears.
The group then travels to Atlantis. They have an adventure that ends up with them popping the oldest living bubble and the Atlanteans hating the group. At the end of the adventure, the king, Lord Royal Highness, however, asks one of his guards to dispose of it in order to prevent from the evil hands.
In the SpongeBob's Atlantis SquarePantis version, the path is much longer than the one in the Atlantis SquarePants version.
Atlantean Amulets also serve as rewards for completing each level in SpongeBob's Atlantis SquarePantis.
If a player reaches a certain time or amount of points in a level, the player receives a medal.
There are three of them. One is gold, and is worth three points. One is silver, and is worth two points. One is bronze, and is worth one point. These points can be used in the shop to buy unlockables such as level variations, art, mini-games, and parts of a "mini-game" called, "SwapBob SpareFace," which allows the player to change what SpongeBob looks like on the main menu screen and in the level description.