I am not quite sure...I know Father sang to Lord Malleus' egg to get it to hatch.

[ Mostly because he peeped in on him doing so, which is probably too intimate of a thing to share, but he wants to help Riddle. Besides, he's not giving away all the exact details, so it should be safe to share...unless Father finds out and grills on him why and how he knows all that. He'll just hope that never happens. ]

Have you tried singing to it yet? I know a few songs that might help...