In 1892, Frank Burns of US. Geological Survey found strange coffins in the Crumf Cave in Murphy’s Valley, Alabama. The wooden coffins appeared to be hollowed out by fire, then chiselled with stone or copper tools. Each coffin was 7.5 ft long, 14-18 inches wide, and 6-7 inches deep. Eight of these coffins were sent to the Smithsonian, which suggested the coffins might actually be troughs. In 1992, the Smithsonian declared that the coffins were housed in a warehouse that would be closed for the next 10 years.