Although their previous lives are unknown, they were presumably buried in the Pyramid of Aggro, a structure in a desert region of Shanazar. However, when archaeologists came to study the pyramid, they supposedly woke the mummies and were put in danger. Fortunately, Sonic the Hedgehog and Amy Rose were in the area and engaged the undead in battle. The hedgehogs fought well, although one of the mummies was able to strike the back of Sonic's head with a strong punch. The blow temporarily disabled Sonic as he suddenly remembered his arrival in Shanazar and the pursuit of the Transportation Belt. As Sonic hallucinated, another mummy prepared to kill him by throwing a rock on his head. Fortunately, Amy was on the ball and kicked the mummy's back, forcing him to drop the boulder on his own head.