“This morning I discovered a worm swimming in my toilet.” So starts a reader’s email that we were sent a few days ago. (The reader originally contacted us through our All About Worms Twitter account.) The reader goes on to say he believes the worm in his toilet is a hammerhead worm, and indeed it looks exactly like a hammerhead worm, but he wasn’t particularly worried about identifying it. Rather, he was curious how the worm got in his toilet. He was wondering if it was possible that the worm navigated its way through his pipes to the toilet, perhaps coming up from the sewer. He also wondered if his “worst nightmare [had] been realized,” which is that the worm somehow came out of his body. So, the question before us is: how did a hammerhead worm end up in a toilet?