Photo taken on May 31, 2019 shows a deep-sea crab collected by Discovery, a remote operated vehicle aboard China's research vessel KEXUE (Science), in western Pacific Ocean. KEXUE finished its investigation of seamounts in the west of the Pacific Ocean and started to sail back on June 15. During the expedition, Discovery, a remote operated vehicle aboard KEXUE, made 19 dives and captured more than 800 collections of biological samples, including corals, sponges, shrimps and shellfishes. "There are about 250 species in the collections, amounting for the total species we had collected in two expeditions in past few years," said Xu Kuidong, chief scientist aboard and a researcher of Chinese Academy of Sciences. (Xinhua/Zhang Xudong)