Photo: Miles Pocket Watches
Oobject, a neat visual directory of gadgets, has an interesting list of Memento mori watches. Memento Mori, latin for "Remember that you will die," is an art genre that span a wide range of styles, but has one purpose: to remind you of your own mortality.
This one above, the Skull and Bones pocket watch, is listed by Miles Pocket Watches as an original creation based on a form of watches made nearly two centuries ago.