Not been reading the series recently... but I noticed that these are classical elements
Roughly fire, earth, sea, air and void. Which fits the japanese element system.
Unsure of the meaning though.
Edit: I've recently learnt that Voldemort real name was Tom Riddle, did he like riddles in canon? It could just be Voldy checking to see how strong his horcrux's influence was on Harry?
One might say it sounds like something of a riddle.
That is, it sounds like something Riddle would say.
Update: This post has also been superseded - new comments belong in the latest thread.
The second thread has now also exceeded 500 comments, so after 42 chapters of MoR it's time for a new thread.
From the first thread: