These same portals could also lead to parallel universes and to Earth. Sonic the Hedgehog, Amy Rose, and Tekno investigated a number of these Zones and portals in the Time Zone story arc. While Sonic initially sounded like he was doing it for fun, in Splitzoid Amy said that they'd been worried that people from the other side of the portals might try to attack Mobius. This happened twice: the aforementioned Splitzoid attack and the alien Set.