Since people don’t seem to be noticing matheist’s answer, I’m copy-pasting it here:
He talks to Quirrell later about not making the obvious suggestion in front of Dumbledore, and goes on to say:
“If you happen to see a stone with that symbol,” said Harry, “and it does talk to the afterlife, do let me know. I have a few questions for Merlin or anyone who was around in Atlantis.” (Ch. 40)
Since people don’t seem to be noticing matheist’s answer, I’m copy-pasting it here: