The Ailouros Pearl is a legendary red-streaked box crab, slightly larger than the other specimens and colored almost entirely white, barring the black markings on its arms (contradicting the name of its base species). It is found only in Endless Ocean 2 within Valka Castle.
The title "Lucky Streak" is obtained upon discovering it.
"Called the pearl of Ailouros Island, this is a rare red-streaked box crab with a pure white shell which can be found only rarely in the Cyclades Islands. Its shell is valuable as it is crafted and sold as traditional art. Popular belief says that whoever finds one of these rare crabs will have the luck of 100 four-leafed clovers."
[The Ailouros Pearl]
"To the west of Ciceros Strait, the cat-filled island of Ailouros (which means 'cat' in Greek) is famous for craft items made from the shells of red-streaked box crabs, as are the Cyclades Islands in general. In the 12th century the shells of Ailouros Pearl were used to make an ornamental white cat known as the Ailouros Cat, which is highly valued among the arts of the Aegean Sea. The figure is so well-loved that replicas are sold today in souvenir shops in the region."
The Ailouros Pearl can be found in Ciceros Strait's Valka Castle in the Mermaid's Ballroom, under a zoom-mode glow just in front of the throne. There are no special requirements that need to be met in order to discover this creature, other than the fact that the player must have Oceana with them (making him one of five legendaries in the game to have this requirement). Since she accompanies the player during their first dive to the castle, it can be found there during said dive if the player checks the correct zoom-spot. On subsequent visits, however, the Ailouros Pearl can be found with or without Oceana's help.
The Ailouros Pearl behaves like other crabs, hiding its face behind its oversized claws and occasionally scuttling about slowly. The player can obtain its trivia information by feeding it.
- This is one of Jean-Eric's favorite creatures.
- The Ailouros Pearl is one of only seven legendary creatures who can be found during the player's first visit to their landmark of residence, the others being the Ice Cupid, Gungnir, Lady Dorthea, the Leviathan, Okeanos's Guardian, and the Singing Dragon.
- The Ailouros Pearl is one of seven benign legendary creatures whose home is often patrolled by dangerous creatures, the others being the Anomalocaris, Apollo, the Ancient Mother, the Grave Keeper, Lady Dorthea and the Living Fossil. In Ailouros' case, a luna lionfish can be found hovering above the nearby throne.
- The Ailouros Pearl is one of only two legendary creatures in the game to be found under a zoom-mode spot, the other being the Ice Cupid. They are also the only two legendaries to not be introduced via cutscene, but have their introductory dialogue play before the player can focus on them.
- Peculiarly, the two also share a page in the Marine Encyclopedia, despite the general lack of similarities between them.