Tidepool Tim says,  “Flatworms look like mini flying carpets as they move along the seafloor or on rocks.  These are the most common flatworm we see in our area.  There seem to be other unidentified flatworms.  Flatworms have eyespots near the head and a simple gut.  These are called worms, but they do not have parapodia or segments like most worms we offer.  They reproduce sexually and asexually.  Food is scavenged from the surfaces on which they live - can be algae or settled larvae of many marine phyla.  Topside of these worms is dark in color while the bottom is usually much lighter - this is protective coloration.  Like freshwater planaria - marine flatworms are an interesting specimen to observe in captivity and are quite easy to keep in any coldwater aquarium.”