This is a Buddha's Hand - it's a citron with very little juicy flesh and a strong lemony smell.
The peel is candied or it's used as an air freshener. Or that's what I'd heard. So I went across the harbor to Kowloon to track one down, brought it home, and, well, I guess it could scent a room. In a dollhouse. Or maybe if you got a couple of hundred and suspended them from the ceiling of a very small and unventilated room.
These are some creepy-looking mushrooms I've been wanting to try.
I added them to a stir-fry last night and, while they seemed to have no discernible flavor, they looked like worms, so the experiment was a success.