In 2012, Dr. Jarrod Burks of Ohio Valley Archaeology, Inc., conducted a magnetic gradient survey of Serpent Mound that detected changes in soil magnetism caused by past ground disturbance. The survey's most notable result was a large U-shaped feature near the Serpent's neck that appears to represent an ancient surface buried by an embankment later removed. If that interpretation is correct, the original builders of Serpent Mound, or perhaps a later group, altered the mound's design at some point in the past, though the reason remains unknown. Magnetometer survey data showed traces of what may have been a former portion of the Serpent erased in antiquity, and archaeologists from Ohio Valley Archaeology, Inc., assisted by volunteers, later excavated a trench across part of the lost coil feature. Their results suggested that part of the mound had once covered that location.