A Navy dolphin training to look for mines off the coast of San Diego found a museum-worthy 19th-century torpedo on the seafloor, military officials said.
The brass-coated, retro wonder of technology was one of the first self-propelled torpedoes used by the U.S. Navy. Just 50 of these so-called Howell torpedoes were made and only one other example has been recovered; it sits in the Naval Undersea Museum in Keyport, Wash., outside of Seattle.
The 130-year-old, 11-foot-long (3.3 meters) weapon was discovered back in March during a mine-hunting exercise that the Space and Naval warfare Systems Center Pacific (SSC Pacific) was conducting with bottlenose dolphins. [Top 10 Animal Recruits in War]
"Dolphins naturally possess the most sophisticated sonar known to man. They can detect mines and other potentially dangerous objects on the ocean floor that are acoustically difficult targets to detect," operations supervisor Braden Duryee, of the SSC Pacific Biosciences Division, said in a statement.
Dolphins use their natural sonar, called echolocation, to determine the size and shape of underwater objects by sending out a series of clicks that bounce off their targets and boomerang back to them. The marine mammals can be trained to report what they have found to human handlers using certain yes or no responses. Handlers can then investigate what the dolphins find by sending the animals to mark an object's location with a weighted buoy line.
In this case, one of the dolphins indicated to its handler that it had detected a minelike target. The recovery dive team initially thought the dolphin had found an old tail section off an aerial drop mine, according to a statement from SSC Pacific, but officials soon realized they were handling a much rarer artifact.