Australia isn’t the only place using sea slugs to learn more about climate change. A particular species, the Hopkins’ Rose nudibranch, turned California’s central and northern coastline pink a few years ago. Researchers from the California Academy of Sciences, UCSB, UCSC, and Bodega Marine Laboratory began tracking the unusually high distribution of this bright pink sea slug in January 2015. Though Hopkins’ Rose nudibranchs are a common sight in southern California, it is unusual to see them in significant numbers further north, as the water temperature is usually too cold to sustain large populations. The presence of this particular species of sea slug is thought to be indicative of major climate shifts, and unexpected population booms could be used to measure future changes.