The Ancient Altar is the pick of the two if you want to gather the most in one go, holding three of the four marked spots against the single one at the Mountain Sanctum. A Fossil Pile is a container you interact with on the map, and the Egg Heist map carries four of them in total. If you are only passing through once, the Ancient Altar gives you the better return for your time, since three spots sitting close together means less back and forth before you have cleared them out.
Areas with Fossil Pile
| Area | Level | On the map |
|---|---|---|
| Ancient Altar | — | 3 |
| Mountain Sanctum | — | 1 |
The Mountain Sanctum is worth the detour if you would rather not crowd all your work into one place, spreading the route out and giving you a reason to range wider. Whichever you pick, park up near the marked spot and cover the last stretch on foot. Keep an eye out as you go, because an Exquisite Relic Chest, a Simple Stone Sarcophagus and an Ornate Wooden Chest each sit within sight of about half the spots, so you can fold them into the same trip.
Open the Aniimo interactive map to see it with every other filter, or pick another from the list.