Convolutriloba is a genus of marine acoelomorph worms. They possess shield shaped bodies with a rounded anterior and three caudal lobes, though the number may vary in mature individuals. They may have an indentation on each side of the body near the anterior end. They usually are a few millimeters to a centimeter in length and under a millimeter thick. Though they have muscles throughout their body, they move using cilia to glide. Due to their rapid growth in well-lit aquariums, they are considered pests.