A system for endoscopically forming an anastomosis between two naturally adjacent points in the digestive tract. The system utilizes elongate magnetic devices that, when connected across a tissue boundary, necrose tissue until an anastomosis forms and the devices are passed naturally. Despite the elongate shape of the devices, the resulting anastomosis is substantially round. As such, round anastomoses can be formed having increased diameters merely by increasing the lengths of the devices, obviating the need for wider endoscopes.