Infested Cobblestone is a deceptive variant of cobblestone that spawns a silverfish when broken without Silk Touch. It has the same texture as regular cobblestone but breaks significantly faster. When a silverfish is attacked nearby, other hidden silverfish in surrounding infested blocks emerge to attack the player. Infested Cobblestone cannot be obtained in item form and is available only through the Creative inventory or commands.

It generates naturally in woodland mansions, specifically in the rarely generated End portal room. It can also be created when a silverfish burrows into regular cobblestone.

Breaking an Infested Cobblestone block with any tool, except one enchanted with Silk Touch, releases a silverfish that immediately attacks. Infested blocks take half the time to break compared to their normal counterparts, making them identifiable when mined. In Java Edition, they can also be distinguished using the debug screen. In Bedrock Edition, placing a note block on an Infested Cobblestone block produces a flute sound, while regular cobblestone produces a bass drum sound.