Black Key

Allows you to open treasure chests and gates. You can store up to 8 black keys, for use on later levels.
Gate

Can only be unlocked if you have a black key.
Treasure

You need a black key (or 2 or 3) to unlock a treasure chest. When opened, it will throw out an assortment of goodies.
Black Treasure 1

You need a black key to unlock this treasure chest. Be careful when you do. It could be good. It could be not so good.
Black Treasure 2

You need 2 black keys to unlock this treasure chest. When you do, it will throw out some extra time potions, and maybe some spikes.
Coloured Key

Allows you to open same coloured gates and treasure chests.
Coloured Gate

Can only be unlocked if you have a same coloured key.
Coloured Treasure

Can only be unlocked if you have a same coloured key. When opened, it will throw out an assortment of goodies.
Lever

There are 4 different coloured levers (red, blue, green and yellow). Pull a lever, and all the same coloured trap walls will vanish.
Trap Wall

There are 4 different coloured trap walls. They will block your way, until you can pull a same coloured lever.