You're right, Linty. That COULD be a skeleton key, but it likely isn't (and it certainly isn't without a lock to accompany it!) Skeleton keys are of that style of key though.
^ Unfortunately in my newbishness I have no idea what a mortice/lever lock is... I mean, I know what a pin-tumbler lock is...but...*sigh*
A mortice lock basically means a lock built into the door itself, rather than through the hole for the deadbolt or through the knob. Usually the face is flush with the side of the door.
A lever lock is an older style lock they use mostly in Europe. Basically the key turns a bunch of round bits with notches or somesuch. The notches allow different levers to be at different levels within the lock. Almost by definition they're mortise, it would seem. You can use the search function to find some nice examples around here.
But the point of the post is probably just that you need different tools for different locks (or just a big drill, but I don't think you could even loosely define that as being a skeleton key).