Digital archivists who’ve been steadily documenting old versions of Minecraft hit a treasure trove this weekend—thanks to programmer and Twitter user Luna (@lunasorcery), they now have access to a very rare version of Minecraft that was only available for 4 hours in 2011: Minecraft Alpha 1.11. The update is a notable one in Minecraft’s history, as it’s the one that introduced features like the fishing rod and ducking. But most players only encountered this update as Alpha 1.12, since 1.11 contained a bug that caused the game to crash to a grey screen. Mojang managed to ship a fix for the bug within a matter of hours, and took down version 1.11.