White whale

The English called the beluga the "white whale", a name often still used (and not to be confused with the white whale of Moby-Dick, which was an albino sperm whale).

No … no sapphires. It looks like Lester Velasquez was chasing his white whale. There never were any sapphires inside that diner.

For nearly four years, Snapchat has been Facebook’s white whale.

After being lofted into space by a Falcon Super Heavy, his next rocket, the Starship, will light out for the moon, land there, take off and return to Earth, with no stages expended on the lunar journey. This so-called single-stage-to-orbit model has been the white whale of rocket designers for generations.