Meet Halgerda wasiniensis (1st pic), a gorgeous nudibranch that like many of the over 3,000 other species of nudibranchs in the sea, has no common name. Sea slugs like the three pictured here have extremely specific diets and short life cycles lasting less than a year. This makes them great indicators of environmental change, as the changing ocean conditions affect the availability of their food and this effect rapidly ripples into nudibranch populations. For example, with ocean warming and acidification, the population of some nudibranch species will fall due to a loss in their favorite sponge snack, while other species will rise in numbers due to a gain in their favorite hydroid snack. While many scientists claim that these colorful, photogenic, and endlessly diverse creatures serve little purpose in the ecosystem and deserve little focus in research, universities in New South Wales, Australia are recruiting 'citizen science' divers and underwater photographers to uncover new species and map ocean health by documenting species abundance. I certainly wouldn't call that useless.