They were rocks owned by the Zombie Force. Gerald 4 broke into a lair to get them. They're are an unknown amount of them. They were used to be studied for perhaps germs. The zombies purposely touched them to see if anyone would fall for their tricks, but they failed since they got it anyway. The rocks were in a box. Sometimes zombies would sleep in this box. Cone Head delivered a note explaining he is coming after them for stealing the rocks. However, this was actually a trap. After The Geralds left, Cone Head came back to steal this box. It turns out there are no zombie germs, rather it was just planktons.