The Head of Olnaxle
This magical lead vessel has as its primary use a very powerful seal. The lid will only open when the name of the person whose visage it bears is spoken. The fact that its construction is of lead should be a tip to players that its contents are of a magical nature as lead is often used in magic resistant materials. This particular lead head contains most likely Saurian Pitch which leaches poisonous gases (con save 15 or contract Saurian flu) and may be used in abyssal rites. It value to the right magic user (one with an abyssal pact or a Saurian adept) could be as high as 1000 gold bits whereas to anybody else it would fetch no more than 200 silver bits as a collectors item.
The name belonging to the visage could either be revealed by having a separate piece of ephemera in the compound with it, the face could appear in a scroll in a library in a different location, or there could be a rebus scribed onto the bottom of the head somewhere.
A detect magic won't penetrate the lead unless the magic user is of a higher level (say 5 or higher e.g.) but an aura of enchantment will appear around the ears as a residual of the magic locking system.