Jungle Key

 can be obtained from killing the Jungle Key Guardian which has a chance to drop Jungle Keys, or by buying it directly from Odawa for 500 Sludge Juice. It is currently used to open the Jungle Temple door.

Jungle Key Guardian
The Key Guardian can be found in a room made of granite in the Jungle of the Crystal Hollows and has a chance to drop Jungle Keys. Attacking the Jungle Key Guardian will cause nearby Kalhuiki Tribe Members to attack the player. Respawns every 1.5 minutes. If there is a player nearby, but they aren't moving, a key guardian will not spawn.