Scarab (Scarab of Death)

A crystal scarab found in Cairo in 2541 was actually a micro-circuit key to release Horus from the Black Pyramid on Beta Osiris.

The scarab was found by Edwin Carver on a dig in Cairo. It sat in a museum storeroom for twenty years until Carver, plagued by gambling debts, decided to sell it to Anwar Nazir. Before making the exchange, Carver learned the scarab's true purpose and refused to complete the deal. Nazir had him killed but the scarab was recovered by the Fourth Doctor and Sarah Jane Smith.

Captured by Nazir, the Doctor handed over the scarab. When Nazir tried to use it, his body disintegrated, because the Doctor had damaged the scarab. With the scarab now useless, the Doctor decided to keep it. (PROSE: Scarab of Death)