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

2. How to Recognize a Hammerhead Worm
Spotting a hammerhead worm is fairly easy once you know what to look for. Its most distinctive feature is the widened, flattened head shaped like a spade or hammer. This sets it apart from typical garden worms. The body is long, narrow, and noticeably flattened.

Color patterns can also help with identification. Many are brown or gray with darker stripes along their bodies, while some appear more uniformly colored. They tend to show up in damp places—gardens, beneath rocks, or on patios after rainfall—since they prefer moist conditions.