Invasion Timer is a Kero Ball-like device as reminder for the Keroro Platoon to be ready for the destruction of Pekopon, it is cleary seen is Keroro's biggest fear. Keroro named it Mash after the Invasion Timer animates itself, later on it turned out to be Kiruru. after it hatches from the Invasion Timer.
Another one resembles the Invasion Timer, but it analyzes how much the cash would cost instead of the countdown for the invasion.