TOYAMA — A rarely seen deep-sea fish regarded as something of a mystery has been giving marine experts food for thought recently after showing up in large numbers along the Sea of Japan coast.

The "ryugu no tsukai" (slender oarfish) — or "Messenger from the Sea God's Palace" — has a long, slender reddish fin and has been compared with a snake. It is akin to an oarfish, which has a dorsal fin running the length of its body and has been called a sea serpent.

There have been reports of the fish being caught in stationary nets or drifting ashore since the start of winter. Some people theorize the phenomenon may foretell a big quake, but others aren't so sure.