Great Crystal Choir Crown
From Tardis Wiki, the free Doctor Who reference
The Great Crystal Choir Crown of Pseudolonica VII was considered the wisest and most beautiful piece of jewellry in the universe. It held spiritual wisdom in its ever-evolving lattice.
Two versions of the crown existed in the Doctor's TARDIS, as a result of the Fourth Doctor "borrowing" them two Christmases in a row as a present for Romana II. The Doctor taught both crowns to sing. He planned to return the crowns before they would be missed. (PROSE: Present Tense)
