Paddle-worms are by far the largest order of polychaetes, with some species getting physically quite large. However, those in the Genus Eulalia are fairly small, i.e., less than 5 inches (12 cm) and can make fairly good hunters of other worms and very small crustaceans (copepods/amphipods) in reef tanks. Easily identified by their fleshy paddle-like projections along each side of the body. May or may not be something you want in your reef tank, however, anything much larger than a few inches should be removed. Take note, they will quickly multiply in tanks that are overfed.