A whale so rare only 7 carcasses have ever been found.

Also there has never been a live sighting.

https://apnews.com/article/rarest-whale-zealand-spade-toothed-dissection-d71aad4ce6e47f4e1056a10cf5b8610e]

WELLINGTON, New Zealand (AP) — It is the world’s rarest whale, with only seven of its kind ever spotted. Almost nothing is known about the enigmatic species. But on Monday a small group of scientists and cultural experts in New Zealand clustered around a near-perfectly preserved spade-toothed whale hoping to decode decades of mystery.

“I can’t tell you how extraordinary it is,” said a joyful Anton van Helden, senior marine science adviser for New Zealand’s conservation agency, who gave the spade-toothed whale its name to distinguish it from other beaked species. “For me personally, it’s unbelievable.”

Van Helden has studied beaked whales for 35 years, but Monday was the first time he has participated in a dissection of the spade-toothed variety. In fact, the careful study of the creature -- which washed up dead on a New Zealand beach in July — is the first ever to take place.

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The list of what scientists don’t know about spade-toothed whales is longer than what they do know. They don’t know where in the ocean the whales live, why they’ve never been spotted in the wild, or what their brains look like. All beaked whales have different stomach systems and researchers don’t know how the spade-toothed kind processes its food. They don’t know how this one died.