During your travels you will encounter a most unpleasant invention of the Robots, Monster Cages.
When Monsters are causing the Robots a headache they employ the Heli Bots to deal with the problem by dragging off attackers to a Monster Cage (see also Heli Bot)
If one of your Stompies is captured the rest of the herd will need to rescue them.
Usually there are only one or two Monster Cages in any location, however the Robots have built larger “Prison Colonies” where there may be many Monster Cages built and a hefty guard in place. (see Prison Colony)