It's been nicknamed "the loneliest whale in the world". It sings a song like no other. It calls at the very unusual frequency of 52 Hz. This pitch is a much higher frequency than that of the other whale species with migration patterns most closely resembling this whale's – the blue whale (10–39 Hz) or fin whale (20 Hz).
Some say it wanders alone across the Pacific Ocean, crying out for companionship that never comes.
No-one knows for sure whether the whale is male or female, what species it is, or even if it still lives. The last in the original series of recordings was made in 2004.