Starconch is a Local Specialty material that can only be found in beaches around Liyue and Dragonspine, it can only be used to Ascend one character (Tartaglia) besides that it has no other use so far, there are a total of 76 on the map at one time and once collected you will need to wait 2 days for them to respawn.
Characters that use Starconch for Ascension
Starconch Map Locations
You can find this map by going to Teyvat Interactive Map website and search for all the materials you need, note that once you farm one of these Starconch you will need to wait 2 days for it to respawn again.
Other ways to get Starconch
- Buying From NPC