In Ultima Online, the Stone Cache appears during special treasure-hunting events, most notably the 20th Anniversary “Shattered Obelisk” storyline. Instead of uncovering a normal treasure chest, players may encounter a Mysterious Obelisk rising from the ground when they decode and dig at a treasure map location.

To access the rewards, the obelisk must first be destroyed by targeting and breaking the glowing green crystal at its peak. Once the obelisk collapses, it leaves behind a Stone Base — also called a Stone Cache — which functions exactly like a standard treasure chest.

The Stone Cache is trapped, requiring players to carefully remove the traps with skills like Remove Trap or spells such as Telekinesis before opening. As adventurers begin looting the cache, waves of guardians and additional monsters may spawn to protect the treasure, keeping the encounter challenging until the container is emptied.