This National Sea Slug Day, celebrate the addition of 17 new species of nudibranch to the tree of life. Adorned in lavish patterns and colors that range from yellow polka dots to shades of mauve and neon blue, the new marine invertebrates hail from coral reefs across the Indo-Pacific region. The team also identified a number of distant relatives that have independently evolved the same color pattern — a first-ever genetic confirmation that color mimicry is widespread in the sea slug world.