I think people associate this chest with a mythical timer for the next chest that supposedly starts after opening the spirit bloom chest. What must have happened was someone went passed the next chest (lower) and that's what makes the lower chest disappear. This happened to us, we did not know what happened since we skipped the spirit bloom chest; but it happened again after we grabbed the spirit bloom. We found out it was our impatient friend who ran passed the chest down to the gorgons.