Minecraft wiki entry for Ice_Bomb, associated text: Ice bombs explode upon hitting most blocks, including non-solid blocks, but not air. They also explode upon hitting other entities, but they do not deal damage, and unlike eggs and snowballs, the impact is not considered an attack and does no damage or knockback. When exploding, any water (including flowing water, but not waterlogged blocks) in a 3×3×3 cube around the ice bomb freezes into ice. Ice bombs can be used to contain and displace mobs in ice under water.