Roman siege engines BC, and surrounded by Roman fortifications. As was standard siege technique at the time, "ballistae" were placed up in the towers with other soldiers armed with either bows or slings. The onager was a post-classical Roman siege engine, which derived its name from the kicking action of the machine, similar to that of an onager (wild ass). It is a type of catapult that uses torsional pressure, generally from twisted rope, to store energy for the shot. The onager consisted of a frame placed on the ground to whose front end a vertical frame of solid timber was rigidly fixed;
Service animal Service animals can be of many species and come in many sizes. Dogs, cats, dolphins, miniature horses, monkeys, ducks, ferrets, and parrots have all been trained to perform specific duties of a service animal, though the type of animal that may be registered as a "service animal" may vary depending on legal definitions. The people that can qualify for a service animal can have a range of physical and/or mental disabilities. A "guide animal" is an animal specifically trained to assist visually impaired persons to navigate in public. These animals may be trained to open doors, recognize traffic signals, guide