SANTA CATALINA. (AP) — Santa Catalina Island harbor patrol has found the carcass of a 17-foot-long sea serpent — a rarely-seen oarfish.

The Orange County Register reports that it is not known how the fish died or how it ended up near the beach Monday.

Because oarfish dive more than 3,000 feet deep, sightings of the creatures are rare and they are largely unstudied. The creatures can grow up to 50 feet long.

Mountain & Sea Adventures employee Miranda Prado says it took 16 people to pick up the fish. The oarfish was donated to several organizations for scientific research.

In 2013 two dead oarfish washed up within days of each other. An 18-foot male was found on Catalina Island and a 14-food female appeared in Oceanside.