When you think of sea slugs, you might envision dark, slimy relatives of the slugs you see in your garden. But one group of sea slugs, the nudibranchs (pronounced “nood-i-branks”), are gaudy, fascinating creatures. They come in a wide array of bright colors and psychedelic patterns. Many have gills that stick up from their backs like clumps of water balloons, shag carpets, or Mohawk hair-dos.