Clair Obscur: Expedition 33 contains 9 Lost Gestrals required for the trophy/achievement Lost Gestrals. Lost Gestrals are found throughout the Continent, and when interacted with will return to their Caretaker Sastro who is located down the side path of the Camp. Speaking to him after finding the Gestrals causes him to give you a reward for each one rescued.
For all other collectibles by story order and by type, refer to Clair Obscur: Expedition 33 Collectible Guide.
Lost Gestrals
Gestral Games are listed in the order they can be encountered and completed through progression of the story. Unfortunately there is no way in-game to know which you have already completed without individually checking each location or checking for the unique rewards some give.
Lost Gestral #1
Near the entrance to Esquie’s Nest main area, speak to it and offer to let it stay at the camp.
Lost Gestral #2
On the path to the right of the entrance of Stone Wave Cliffs main area, beat the Bourgeon miniboss to reach the Lost Gestral just past it on the right.
Lost Gestral #3
West of the entrance to White Tree side area by the tall green plants.
Lost Gestral #4
On north edge of the green area between Forgotten Battlefield and Monoco’s Station main areas.
Lost Gestral #5
On the red island northwest of the back exit of Old Lumiere main area, past the pair of Mimes.
Lost Gestral #6
On small beach near three enemies directly north of Coastal Cave side area.
Lost Gestral #7
On a floating island on the south side of the Endless Tower very high in the air.
Lost Gestral #8
In a location you can reach by flying slightly northeast of The Reacher side area.
Lost Gestral #9
On the east side of the map is a red forest area you can fly to. On the south side of the path opposite the entrance to Endless Night Sanctuary side area you can find the last Lost Gestral. This unlocks the trophy/achievement 
Lost Gestrals immediately, but make sure to return to camp and speak with Sastro for your rewards. For finding the final Lost Gestral you receive the Pro Retreat Pictos from Sastro.
That’s all Lost Gestrals in Clair Obscur Expedition 33. For all other Collectibles check out Clair Obscur: Expedition 33 Collectible Guide.
