 The free cheeks of the cephalon formed a pair of long, curved spines, and the segments of the pleural lobes were separated and elongated to form rib-like struts.These modifications, along with the "V" shaped pygidium give these trilobites a cartoon "fish-skeleton" appearance.The defensive value of these highly elongate spines is also apparent, as they would have stuck in the throats of vertebrate predators, such as the Silurian acanthodian "Nostolepis".