Vault
A vault is a structure used to store prison and exile-pearls and other valuables. A vault, in it's most basic form, is typically an obsidian pyramid, as this is the hardest structure to destroy. To protect this pyramid, other fortifications may be built around it, such as rings of obsidian walls, cobwebs and bastions, sometimes referred to as "nerd rings". A bunker or tower is often constructed above the vault, where supplies for fighters are stored.