In the Desert, after you get the first scarab, and go past the two connecting trees, there are 2 columns holding up the higher floor. Kill the snake and go BEHIND the second column. Jump up and you'll fly up the a secret place. There is a merchant there where you can trade gems for Extra Lives (5 gems) or Continues (10 gems). To get down, go to the very left, and there are stone steps that you can go down and continue your mission.