While surveying whales and dolphins off the Hawaiian Islands, scientists spotted a creature they've never seen before: a peculiar hybrid between a dolphin and a small whale.

In 2017, before future naval officers trained on submarines in the waters around Kauai -- a place called the Pacific Missile Range Facility -- the U.S. Navy hired marine researchers from the Cascadia Research Collective to study the native animals in these seas. After encountering a large pod of melon-headed whales, the researchers tagged two of them, to see where they might go.

It was then that the researchers noticed something curious about one of the creatures. It wasn't quite a melon-headed whale. Nor was it exactly a rough-toothed dolphin, which are common to the area.

They collected some tissue from the animal, and after returning to shore and performing genetic testing, discovered it wasn't either species, but both.

The hybrid was especially rare because of its melon-headed genes: The toothed-whales are rarely seen in these Hawaiian waters, the researchers wrote. Both species belong to the Delphinidae(oceanic dolphin) family, but the report notes that cross-species unions between them are unusual: It's only the third recorded example in the Delphinidaefamily, and the first between these two species.

The hybrid, however strange, certainly wasn't treated as an outcast. The marine scientists tagged the hybrid with satellite tracking GPS, along with a companion, to see where they might go. And it appears they stayed together, travelling some 475 miles over eight days, and diving thousands of feet beneath the surface.