So, if you haven't already (after my posting a record three times in one day!) go to my Harry/Draco Worldcup Entry here: primum mobile, or ten forgotten things.
And as additional author's notes, the forgotten things are: Hogwarts Castle, ticket, scarf and tie, Galleons, pocketwatch, wand(s), first meeting, Hermione's face, Quidditch, and Potions.
A primum mobile is an old astronomical device, which you can look up here. It is the 'first mover', an outer circle that, when moved, sets all else in motion.
Edit: I've gotten enough online recs to be added to the daily snitch! :D