That's nice that you're thinking of the kids who can't have pets.
Hmm..
Make it a bed. Out of a washcloth or something like that.
Cages? Collars?
Take them out for socialization with other pet rocks?
Train them? No rocks on the furniture...or on the table....
Take them outside three times a day to "use the bathroom".
Exercise, maybe roll the rock or toss it up and catch it.