I've been waiiitiing... five thousand years for this!
— The Mummified Hedgehog, "Robotnik's Pyramid Scheme"
The Mummified Hedgehog wears a linen cloth wrap and an emerald necklace. The emerald around his neck allows him to activate a blue shield that makes him immune to the powers of anyone wearing the Chaos Emerald of Immortality.
The Mummified Hedgehog lets Sonic borrow the emerald from his necklace to defeat Dr. Robotnik, who took the Chaos Emerald of Immortality from Robotnikhotep. After Robotnik was beaten, Sonic returned the emerald and the Mummified Hedgehog went back in his coffin.
The Mummified Hedgehog is the archenemy of Robotnikhotep, which is very similar to that of Sonic and Dr. Robotnik.