The Bobbit worm will give you anxiety.
The worm, specifically, is an aquatic predatory polychaete worm that dwells on the ocean floor. It tends to “ambush” its prey, using a lightning-fast striking method
The worms can grow to a size of about 10 feet, found primarily in the Indo-Pacific and Atlantic. But they can get accidentally introduced into fish tanks and aquariums.
https://www.youtube.com/watch?v=aMorvRRbZ5E
