Ainigmata Ostraka are puzzles available in Assassin's Creed Odyssey. They can be found in various parts of the world - they can be hidden inside of a cave, in an oasis or in enemy camps. Every starting location of an Ainigmata Ostraka can be found on the map. Simply go to that place and pick up the object.
Ainigmata Ostraka consist of two parts: a puzzle/tablet and an item that must be found. The first part of an Ainigmata Ostraka has a tip about a location of the item related to this puzzle. You won't get an exact location. Instead, you will get only a hint.
An item related to an Ainigmata Ostraka can only be picked up after you collect the first part of that particular puzzle.
Collect the second part of an Ainigmata Ostraka to receive a new engraving for your armor or weapon. Thanks to them you can upgrade your gear. However, you won't receive any XP nor skill points.