The Force Field was created by Ben "Sparrow" Wright for Creatures and later adapted by him for Creatures 2.
From the readme file:
This relatively simple COB is used to (painlessly) keep norns and grendels from passing through the beams of the force field. It has many uses, including, but not limited to:
- Quarantining ill norns
- Keeping the grendel in his place
- Isolating 2 norns for teaching/breeding purposes
- Keeping groups of creatures seperated from each other
- Isolating a norn so you can get him to eat/sleep
The COB also turned out to be popular among norn torturers, for keeping norns in their place. A modified version for C1 is available at Muppetboy's Geatville.
The Force Field uses object class numbers: