“Silverfish are small, bug-like hostile mobs which have silver skin and black eyes that hide in monster eggs found in strongholds and extreme hills. The blocks look identical to normal blocks, but when the block is mined, a silverfish pops out and attacks.
When attacked, silverfish may awaken other silverfish within a 21x11x21 area. This can lead to a terrifying swarm if there are enough in the vicinity, and an uncontrolled swarm can quickly surround and kill the player. Left alone, silverfish will re-enter in another block, transforming it into another monster egg.”
Silverfish will spawn by mining Monster Eggs or from spawners inside Strongholds.
Hitting a Silverfish will attract more Silverfish, resulting in a swarm attacking you.
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