You were swimming around the warm ocean, admiring the colorful corals and tropical fishes. While you watch the mentioned fishes swimming around, you saw something coming out of a hole

Mantis shrimp: it was a kind of a shrimp, but not a normal one, it's an Mantis shrimp. Known for their strong punch, It started to kill every fish it sees, with their fists that kills them instantly, and could even harm you. But despite that, it is completely neutral and doesn't seem interested in you. Sometimes it stares at you once finished killing a fish, but eventually ignores you and goes back killing more