A simple guide on how to get a secret chest key from the Casula Temple, deep in the jungle. Spoiler Alert!!!
Head to the room on the left and look for the ray of light on the lower left corner of the room.
Trigger the spot shown in the photo.
If successful, you should hear a sound coming from the right side, and the ray of light would have been gone.
Upon activation, the ray of light should disappear too like in the previous room, and you should also hear the same sound you heard earlier, but this time, coming from the left side of the screen.

Thanks to OneHandGamer for his great guide, all credit to his effort. you can also read the original guide from Steam Community. enjoy the game.
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