A reader has been finding black worms in his toilet over the last couple of months. The worms in the toilet (we should actually say worm in the toilet, as only one is ever found at a time) appear seemingly out of nowhere, and they do not appear to be linked to anybody using the toilet. (In other words, the worms aren’t coming from somebody, which is good.) What are these black worms in the toilet? Is our reader finding a type of worm at all, or might he be finding some kind of larva (or larvae, since he’s found five)?