They can be hunted and when they do, they form large packs (up to ten members) that apear as large clusters on the map. The clusters often are mistaken as one ceolophysis which can be a deadly mistake.
Once the placer is seen, one Ceolophysis will attack the player. The player will have no choice but to shoot it, alerting the others. The others will dart at the player, and try to tear them to pieces.