Great Crystal Choir Crown

The  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)