Ruckleberries are a type of Elvin berry that has many uses. Not only are these yellow and green speckled berries able to purify metal (with immense difficulty) in Alchemy, but they are also able to work as a disguise. It was mentioned in Book 1 that it is uncommon to use ruckleberries to purify metal, as it can cause the skin to wrinkle if their juice gets on it, as well as making the user smell like feet all day. For alchemy midterms, Sophie had to purify a key with these berries. As the ending result, she had made three-quarters of the key the color she was going for, and her pinkie finger was wrinkled for the rest of the day. It was later mentioned that Mr. Forkle uses these berries as a disguise causing him to look like an elderly man. Once again, they are mentioned in book 6, Nightfall, where it so happens that Lady Cadence had stumbled across them in her spare time as the beacon. She finds a garden full of them and connects that Magante Leto is Mr. Forkle.