A mammoth-sized oarfish, which is said to have inspired tales of sea monsters, was found this week on the shore of a Mexican beach.

The large fish was seen swimming in the waters of the Sea of Cortez in Baja, Calif., and was found close to dead 48 hours later on the nearby Isla San Francisco, according to the Daily Star.

Sightings of the fish are very rare, as they live deep in the world's tropical oceans.

The fish is the world's longest bony fish, and is hardly ever seen except when it washes up dead on beaches. Oarfish can grow up to 56 feet, and have a dorsal fin that sticks up out of the water.

Lia Stamatiou, an expedition leader for Un-Cruise Adventures, says she was "completely stunned" when she first saw the fish.

"I learned about the oarfish as one of those fish you study but never see," she said. "Seeing it swim up to us on the beach I was completely stunned.

"It was one of the most surprising and beautiful animals I had ever seen, with fantastic iridescent blue skin and a vibrant red dorsal fin," she continued.

She said that the fish resisted attempts by the crew to push it off the beach and back into the water.

"Eventually it raked itself on the sand to the point of exhaustion, and the birds descended to finish the job," she added.

Two oarfish were found dead on the coast of southern California last year. This recent incident was the first time an oarfish was sighted in 2014.