The researchers found that the worms didn't control the direction of the papilla directly. Instead, they just shot slime out through the papilla, and the speed of the slime through the small opening was enough to make it oscillate, like water speeding through an "unattended garden hose," as the authors noted in a press release. To prove the point, they built a tiny replica papilla out of an elastic tube and sent water through it to see at exactly what speed the liquid would have to travel to start the tube moving. In their experiment, the water started moving the tube around when it got to a speed of 8.6 meters per second (or 19.2 miles per hour). You can see that video below.