Thysanozoon nigropapillosum is a species of polyclad flatworms belonging to the family Pseudocerotidae. Thysanozoon nigropapillosum are commonly named as gold-speckled flatorm, marine flatworm, yellow paipllae flatworm, yellow spotted flatworm, and yellow spotty polyclad. They have a long body and broad shape, and can grow up to 3 inches (76mm). They are widespread in the Indo-Pacific, and feed on tunicates, and later regurgitates food pellets that contain calcareous spicules that are present in their tunics. The Polyclad flatworms are hermaphrodites, with each pair of flatworms attempt to inseminate each other.