The frilled shark (Chlamydoselachus anguineus) is a deep-sea predator often described as a “living fossil” due to its ancient lineage and unchanged appearance since the time of the dinosaurs. With its long, eel-like body and frilly gill slits, it resembles a mythical sea serpent more than a typical modern shark. This rare species has survived in the dark depths of the ocean for over 80 million years, maintaining its primitive features while the world above evolved dramatically. What makes this creature especially terrifying is its mouth, which contains around 300 trident-shaped teeth arranged in 25 tightly packed rows. Unlike most sharks that bite and tear, the frilled shark's jaws are designed to trap. It lunges forward to snag prey usually squid, fish, or even other sharks and swallows them whole. Once something enters its mouth, the backward-facing teeth make escape almost impossible, effectively turning its jaws into a biological trap. Normally living at depths beyond 1,000 meters, the frilled shark is rarely seen by humans. On rare occasions, it rises to shallower waters, offering scientists brief glimpses into the deep-sea world. These encounters serve as eerie reminders of how much of the ocean remains unexplored, and that some of Earth’s oldest and most alien-like creatures still thrive in its darkest corners.