Cryptex

The cryptex featured in the novel is described as a stone cylinder comprising "six doughnut-sized disks of marble that had been stacked and affixed to one another within a delicate brass framework"; end caps make it impossible to see inside the hollow cylinder. Each of the disks is carved with the entire alphabet and, since they can be rotated individually, the disks can be aligned to spell different five-letter words.

The cryptex works "much like a bicycle's combination lock", and if one arranges the disks to spell out the correct password, "the tumblers inside align, and the entire cylinder slides apart" . In the inner compartment of the cryptex, secret information can be hidden, written on a scroll of thin papyrus wrapped around a fragile vial of vinegar as a security measure: if one does not know the password but tries to force the cryptex open, the vial will break and the vinegar will dissolve the papyrus before it can be read.