“These worm-like larvae are on the bottom of my koi pond”, writes Steve about the slimy-looking, dark green-gray creatures pictured below. “I live in the San Francisco Bay Area in California. Trying to ID and control as necessary. Thank you.” This photo has us puzzled. Not only do the reflections in the water make it hard to see the worms’ physical characteristics, but they all share this gray-green color which they seem to be bathing in. We can’t tell if this really is the color of the worms, and they match the background, or if they are covered in some kind of slime or sludge.