Spotted this long worm with a flat, shovel-shaped head slithering on the patio stones. It looks totally unnatural. What is this?

3. Why They Seem So Alien
Many people find hammerhead worms unsettling because of their unusual form and the way they move. Their flat, elongated bodies and distinctive head shapes differ greatly from the segmented worms most of us are used to seeing. Their glossy, slimy surface only enhances their strange, almost extraterrestrial look.

Their movement adds to the effect. Instead of wriggling in segments like earthworms, they glide smoothly across surfaces. Tiny hair-like structures called cilia on the underside of their bodies help them move in a fluid, snake-like fashion. This steady, seamless motion makes them seem even more otherworldly.