A device developed by the U.S. Navy Ordnance Laboratory for sampling coral and sand bottoms. It consists of a four-legged pyramidal frame about 8 ft (2.4 m) high, a pneumatic hammer with air supply and exhaust hosing, 400 lb (180 kg) of lead weight, an anvil, and a 4-ft-long (1.2-m-long) aluminum barrel with a driving head for cutting through coral.