In a comprehensive expedition examining deep-sea ecosystems off the entire length of Argentina, scientists aboard the Schmidt Ocean Institute's vessel R/V Falkor (too) have documented a rare phantom jellyfish. Stygiomedusa gigantea, commonly known as the giant phantom jelly, can grow up to 1 m (3.3 ft) in diameter, and its four arms can reach up to 10 m (33 ft) long. They do not have any stinging tentacles but use their arms to catch prey, according to information shared by the institute. | AFP

Get a glimpse at this bizarre jellyfish—previously unknown to science—that researchers just discovered in the Mariana Trench. | National Geographic