Some time ago a reader wrote to us inquiring about a Nile River worm. The worms in the Nile River stay in there; that is, the worms do not leave the Nile River to come ashore, but live entirely in the water. The reader didn’t have any personal connection with the Nile River worms – they are merely something she had heard of, but now she is unable to track down any information about them. What worms in the Nile River never leave the water?