According to Dr. Helen Magnus, it was so ugly that it developed a method of concealing itself and was said to be extinct. Its main defense mechanism was to climb onto some other, larger creature and inject it with a special pheromone to cause aggression and the need to protect the pinepex. If for any reason the pinepex's current host becomes unable to protect it it'll immediatly go in search of a new host. When the pinepex pheremones leave the hosts body they experience a memory loss of whatever they did as the pinepex host, this is so that the pinepex's former host doesn't know it exists and doesn't go looking for it later.