"If the diary was not a horcrux, then how could Riddle's soul have been there?" Hermione asked.
"I believe you are all missing the most obvious answer," Dumbledore interjected with a knowing smile directed at them all. When no one spoke up, Dumbledore elaborated. "Riddle created his first horcrux with the murder of Moaning Myrtle. Myrtle was killed by the gaze of a basilisk."
"The basilisk was the horcrux!" Remus exclaimed.
"I do believe so," was the Headmaster's reply.
Remus shook his head in wonder. "It's so obvious. How could I have missed that?"
"Sometimes the most obvious answers are those which are the most difficult to find."
It was a piece of sage wisdom Harry would have expected to come from the ancient wizard. But it still did not explain everything.
"Then why did Riddle's shade appear?" he demanded. "Or does this happen with every animal horcrux?"
"There was no mention of it in the records," Remus replied with a frown.
"I expect this is not a normal occurrence," Dumbledore stated. "I have given this some thought, and I believe that I may have an explanation of sorts, though I must stress that it is speculation.
"First, it seems unlikely that anyone has ever made any horcruxes of thousand-year-old basilisks, or any other creature possessing such power, for rather obvious reasons. Thus, I believe that the basilisk may have been somewhat unique as horcruxes go.
"Now, I believe, Remus, that you said items which were intended to be horcruxes are affected to a certain extent?" Remus nodded his head, seeming intrigued with where Dumbledore was going with this speculation. "I would postulate then, that there was a connection of sorts between the true horcrux—the basilisk—and the intended horcrux—the diary—which allowed the horcrux in the basilisk to control Ginevra Weasley."