It is an essential item for the quest "Lost to the Ages." The first one (left piece), can be obtained from Arkngthamz. The others can be obtained from Deep Folk Crossing (upper piece) and Raldbthar (right piece). The lower piece can be found in the Dwarven Storeroom outside Mzulft, without needing to start "Revealing the Unseen." Once the Aetherium Crest is formed, it can be used with the Aetherium Forge located under the Ruins of Bthalft to craft one of three unique artifacts/items: the Aetherial Crown, the Aetherial Shield, or the Aetherial Staff.
If one is obtained before "Lost to the Ages" is started or the book The Aetherium Wars is found, then a miscellaneous quest, "Identify the Crystal Shard" will appear in the quest log.
- Aetherium Shards can be collected before the quest "Lost to the Ages" is started. This will result in a miscellaneous quest to identify the shard, which can be done by reading a copy of The Aetherium Wars. After reading the book, the Dragonborn will be redirected to Arkngthamz, where the actual quest will begin.
- If an Aetherium Shard was taken before "Lost to the Ages" was started, Katria will still spawn near claiming a new shard is found if the Dragonborn returns to its original location.