What is the power of the pearls? (in percy jackson the lightning thief)

They take him wherever he wants he just has to think of the place he wants to go

When he arrives, a nereid gives Percy three pearls saying they are gifts from his father, Poseidon. Percy takes the pearls with him to the Underworld. Hades tries to kill Percy, Annabeth, and Grover when they smash the pearls at their feet, the pearls then carry them to the middle of Santa Monica Bay because, as the Nereid said, "What belongs to the sea returns to the sea."

What’s your question? i’d be glad to out. : )