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Grace O'Brien liked frogs. As a result, both Ryan Sinclair and Graham O'Brien got her a necklace with a frog on it, unaware that the other had decided on the same thing. In order to verify that the Solitract construction of Grace was her, he asked her about the frog necklace. Due to Grace liking frogs, the Solitract took the form of one when talking to the Thirteenth Doctor. (TV: It Takes You Away)