it looks like an upside down tooth
get to the safe zone at the bottom of the screen and draw an hourglass symbol on the door
you go out the door you came in from
after the temple OF ice you use the iron boots in lake hylea and you will see a door, go into it and it will be the door to the temple ( not the one to zora domain)
you draw the letter z
beam the 3 statue lasers on the temple door
You tap the door where you need to go.(temple of courage)
you have to blow to enter and for boss you have to get boss key
you draw the Zelda symbol
The first crest that you draw on the red door is the hour glass symbol . The second symbol you draw after you come back, and the temple has changed is the tri force symbol you draw. That that will take on another route to another level.
the hourglass itself
To get into the temple you need to find the three stone heads and put theire beam on the eye at the door of the temple of courage.
the triforce which is this thing