Bobbit worms are ambush predators. They use their five antennae to sense passing prey, grab it with their jaws, and then pull it underground, where “what happens next is rather unknown.” They’re carnivorous and they have the ability to snap their prey in half. Bobbit worms have been seen feeding on lionfish, pufferfish, and even an octopus!
Here’s an animation I made of a bobbit worm catching a cardinalfish:
Oh, yeah, and they can grow to be up to TEN FEET LONG (about 15 times as long as the average California sea hare). Terrifying.