Blue rock
From Tardis Wiki, the free Doctor Who reference
A blue rock on Belstar was a storage device containing information crucial to the conflict between the Debans and the Siros. The rock was stored by the Siros in the Crypt of Primo, around which the conditions made it unreachable by the Debans. The Sixth Doctor and Peri were therefore sent to retrieve it for them. (PROSE: Battle Planet)
