They discovered a rare 19th-century device that is one of only two in existence.

The discovery itself is notable enough: Navy specialists found a rare torpedo off the San Diego coast, an 11-foot brass gem called the Howell that dates back 130 years or so and was one of the first torpedoes to propel itself.

Only 50 were made, and only one other one still exists. But what makes the story even better is that the Navy specialists who found it were trained dolphins, reports the Los Angeles Times.

“Dolphins naturally possess the most sophisticated sonar known to man,” explains a specialist at the Space and Naval Warfare Systems Center Pacific. “We’ve never found anything like this,” says the head of the Navy’s marine mammal program. “Never.”

Give credit to dolphins Ten and Spetz for finding the torpedo, stamped “USN No. 24,” and then directing human divers to the spot.

The torpedo, rendered inoperable by its long stay in the ocean, is now being cleaned and readied for display at the Naval History and Heritage Command in Washington.

“It was the first torpedo that could be released into the ocean and follow a track,” says another official at the warfare systems center, and that made it a state-of-the-art weapon in its day.