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

5. Are They Harmful to Humans or Pets?
Hammerhead worms do not pose a direct threat to people or animals. They don’t bite, sting, or spread disease. However, they release a toxic slime that can irritate the skin if touched.

Although they aren’t dangerous in a direct sense, their impact on beneficial soil organisms—especially earthworms—raises concern. If you need to handle one, it’s best to wear gloves or avoid direct contact to prevent possible irritation.

6. The Bigger Concern: Their Impact on Earthworms
The real problem with hammerhead worms lies in their effect on earthworms, which play a vital role in soil health. Hammerhead worms hunt by secreting sticky mucus that traps their prey.