Lichida is an order of typically spiny trilobite that lived from the Tremadocian to the Devonian period. These trilobites usually have 8–13 thoracic segments. Their exoskeletons often have a grainy texture or have wart or spine-like tubercles. Some species are extraordinarily spiny, having spiny thoracic segments that are as long or longer than the entire body, from cephalon (head) to pygidium (tail). The sections of the pygidia are leaf-like in shape and also typically end in spines.