A total of 10 Mysterious Shards can be found in Assassins's Creed Mirage. They are part of the main quest "Ancient Place" from Nehal. This quest starts soon after killing the first member of the Order - "Al-Ghul".
The Mysterious Shards can be acquired by pickpocketing or assassinating the characters in black robes, who walk along the scripted paths, usually accompanied by one or two guards. The map shows the places they will pass through, so you can just wait for them to arrive here or look for them somewhere nearby. These NPCs are marked on the map while using the highest zoom.
The Mysterious Shards are needed to unlock three chests in the secret chamber, which can be reached by diving down in the Northern Oasis.
