Super Mario 64 DS Tips

Make all the "?" blocks solid!
When you get 14 stars in the the bit where you arrive when you enter the castle a light will be shining down on the carpet.Press X and look up and you will be transported into a secret world fly down to the middle tower and jump on the "?" button.You have now made the "?" blocks solid!
Save and jump off the edge you will return to the castle and all of the "?" blocks in every level will be solid!