Found in some of the most inhospitable latitudes on Earth, it's no wonder these mysterious creatures remained undescribed by science for so long.

In 1955, a group of 17 animals was found stranded on the coast of Paraparaumu, New Zealand. While they looked like killer whales, they were decidedly different. There heads were rounder and sported a tiny white eyepatch, and they had a narrow and more pointed dorsal fin. Scientists had never described a species like this before ... and thus, the mystery began.

Researchers speculated that the unusual creatures might have been a genetic aberration from regular killer whales – which depsite their name, are actually from the dolphin family.

Fast-forward to 2005, and a French scientist showed some photographs to Bob Pitman, a researcher from NOAA Fisheries' Southwest Fisheries Science Center in La Jolla, California. The images revealed some odd-looking killer whales that had been seen pilfering fish from commercial fishing lines in the southern Indian Ocean. Notably, they had the same unique eye patches and rounded heads.

Now, an international team of scientists have seen the animals – referred to as Type D killer whales – in action and believe that it is indeed a species thus far undescribed by science. After waiting out the perpetual storms of Cape Horn off southern Chile, the expedition was able to collect three biopsy samples, tiny bits of skin taken from the whales with a crossbow dart. The samples will be analyzed to confirm the new species.

Top: Adult male 'regular' killer whale - note size of white eye patch, less rounded head and dorsal fin shape. Bottom: Adult male Type D killer whale - note tiny eye patch, more rounded head, and more narrow, pointed dorsal fin. (Uko Gorter)/CC BY 2.0

"We are very excited about the genetic analyses to come. Type D killer whales could be the largest undescribed animal left on the planet and a clear indication of how little we know about life in our oceans," said Pitman.

Interestingly, some accidental citizen science helped with the breakthrough. With increased tourism in Antarctica, there has been a flood of wildlife photography from the once seldom-visited area. Pitman and his team began to collect killer whale images from the Southern Ocean, including from tour vessels. Occasionally, one of the Type Ds would show up.

"In 2010, Pitman and colleagues published a paper in the scientific journal Polar Biology describing the Type D killer whales. They included photos from each encounter and a map of the sighting locations," notes NOAA.

Based on all the information that had been collected, the expedition was launched. And even though the vessel, Australis, had to wait out more than a week of storms, their encounter with a pod of the elusive creatures was clearly worth it.

As more species seem to be increasingly spiraling toward extinction, it's heartening to know that the ocean is home to more mysteries than we will ever know. While Pitman says this might be largest undescribed animal left on the planet, I'm guessing there's a whole world of creatures in the sea that we can barely fathom. For now, it's nice that an unknown killer whale with a tiny eyepatch can remind us of that.