1. Get the chief to make a lecture
2. Quickly put the chief on the mountain to make a rare collectible appear
3. Pause the game
4. Look for the collectible. Note that coral is found by the beach, tablets near the rubble, turtle shells by the waterfall and feathers anywhere! I find it easier to quickly check the three first spots to make sure it's not a feather
5. Get a kid to pick it up
(The lecture is made so that any villagers standing on collectibles will get off them and go to the ampitheatre.)