Q:I am a movie director and I just received the following movie plot. Could you help me answer this question? If not, let me know by writing "Not answerable". Plot title: The Little Mermaid II: Return to the Sea Movie plot: A year has passed since the events of the first film. In that time, Ariel has given birth to a daughter, named Melody. Ariel and Eric set sail for deeper ocean waters, to have Melody meet her extended family, as well as the residents of Atlantica. King Triton greets his granddaughter with a large smile, and a special locket.Suddenly, the festivities are put on hold as Ursula's sister Morgana arrives, with a shark named Undertow. Morgana claims she's here to exact revenge for the death of her sister, threatening to feed Melody to Undertow. Eric and Ariel manage to rescue Melody, while Triton uses his powers to turn Undertow into a small fish. Morgana and her servant escape, but not before vowing to get Melody.Upon returning to land, Ariel decides that they must keep Melody away from the ocean, to keep her safe from Morgana. Triton sadly agrees, and leaves Sebastian to watch over Melody. As Triton swims away, he drops the locket he had given Melody into a small sea trench near Eric's castle.12 years pass, and in that time, a large wall has been built around the castle. Melody in that time has grown into a young girl with black hair like her Father, and her Mother's spunky attitude. Unknown to her parents, Melody has been swimming under the wall, and out in the ocean in secret. While diving down into a small crevice, Melody uncovers the locket with her name on it, that had been meant for her 12 years ago.Meanwhile, Morgana and Undertow have retreated to an Antarctic region, where they have been in hiding from Triton for some time. Morgana attempts to reverse Undertow's shrunken state, but her magic cannot overcome Triton's. Using her magic to scan the ocean, Morgana sees Melody discover the locket, and figures the young girl can help her get revenge on Triton.Melody has since returned to the castle to prepare for her 12th birthday. However, the party does not go as planned, and through a mishap with Sebastian, Melody feels that she's ruined her own birthday party. Ariel goes to console her, but then finds the... My question: What does Melody use to disintegrate the wall?
A:
Trident