Nautilus
Nautilus is a neutral aquatic mob found throughout Minecraft's ocean biomes, modeled loosely on the real-world cephalopod. Its mouth and tentacles point in the direction opposite to its travel, reflecting the anatomy of its natural inspiration. Untamed adult nautiluses will occasionally dash toward nearby pufferfish and will briefly retaliate if struck by a player, though they cannot be leashed while in a hostile state. They are immune to the Poison effect, and in Java Edition they remain susceptible to the Impaling enchantment.
Nautiluses generate in groups of one to three across all ocean biome variants, between Y-levels 38 and 58. In Bedrock Edition, approximately one in ten spawned individuals will be a baby. A freshly spawned nautilus counts toward the water-creature mob cap until a player first interacts with it, at which point it becomes persistent and no longer contributes to the cap. Babies and tamed specimens are passive toward players at all times.
Taming a nautilus requires feeding it pufferfish or a bucket of pufferfish, with each attempt carrying a one-in-three chance of success. Once tamed, it can be fitted with a saddle and ridden as an underwater mount capable of dashing and bestowing the Breath of the Nautilus effect on its rider, preventing drowning. It can also be equipped with nautilus armor. Feeding tamed adults fish or fish buckets restores their health, and two fully-healed adults can be bred together.
When a nautilus is killed by a player or tamed wolf, it yields one to three experience points and carries a five-percent chance of dropping a nautilus shell. Any saddle or nautilus armor it was wearing will also fall on death.
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