Early in the morning, I stepped outside to get some fresh air when something strange on the pavement caught my attention. At first glance, it looked like a long worm dragging a piece of grass behind it. But when I moved closer, I noticed its unusual flattened body and several dark stripes running from one end to the other.

What made it especially confusing was the shape of its head. Instead of having the ordinary rounded end I expected from an earthworm, its head appeared wider and flattened, almost like a tiny hammer. That unusual feature was the clue that revealed what I had actually found.

It was a hammerhead flatworm, also known as a hammerhead worm. These terrestrial flatworms belong to a group called Bipalium, and several species have distinctive broad or crescent-shaped heads. Their long, slimy bodies and dark longitudinal stripes can easily make them look like unusually shaped earthworms from a distance.

Hammerhead worms are predators rather than ordinary garden worms. They hunt creatures including earthworms and other small soil-dwelling animals. Some hammerhead flatworms also produce tetrodotoxin, so handling an unidentified one with bare hands isn’t recommended. If one needs to be moved, gloves or another barrier are a sensible precaution.

So the strange object on its head wasn’t grass at all—it was part of the animal itself. The flattened, hammer-shaped head that made it look so bizarre is actually its most recognizable characteristic. What initially appeared to be an ordinary worm turned out to be a remarkably unusual predatory flatworm.