Artifact Sonic Underground : Season 1 Episode 13

The Hedgehogs steal historical artifacts of Mobuis from Robotnik before he can pawn them off at an auction. Sonic and Sonia take one of the pieces to a university professor who informs them that the artifact is actually a bomb from the Mobian war. The Hedgehogs must act fast to retrieve the bomb and protect the treasure that is the key to Mobius past.