A species of sea turtle that is rarely seen on North Carolina’s Outer Banks has been found dead in a Frisco marsh near the Pamlico Sound. The Virginian-Pilot reported Tuesday that biologists have so far been unable to find a cause of death of the leatherback sea turtle. The creature weighed upwards of 500 pounds. And biologists solicited the help of a construction company’s crane to lift the dead animal onto a barge. Biologists with the North Carolina Wildlife Resources Commission and the National Park Service found no obvious cause of death. The investigation revealed no physical injuries, plastics in the intestines or major parasites. But the animal’s organs suggested the animal was under physiological stress.