If you’ve watched the nature series Spongebob Squarepants, you may be under the impression that starfish are gentle, harmless creatures. But they’re not. Starfish are effective predators against immobile species. Researchers placed a tiny camera inside a mussel. Watch a starfish digest its victim from close range. The starfish pours caustic chemicals into the shell, then injects its own stomach inside the shell to digest the soupy mass that remains.