From the Super Mario Wiki, the Mario encyclopedia
Paper-Cone Goombas (Paper Cone Goombas in the British English version) are enemies that debut in Paper Mario: Sticker Star. They are a species of Goomba which are first fought in World 1-1, Warm Fuzzy Plains. They appear as regular Goombas during exploration, and do not reveal their true form until a battle is initiated.
Using sticker power, these Goombas can fold themselves into a conical shape, giving them a sharp corner that acts like a spike. Unlike with regular Goombas, Jump-based stickers (with the exception of Iron Jumps) have no effect on Paper-Cone Goombas, and the player must used Hammer-based or other non-Jump stickers.
A trio of Goombas which are previously fought in Decalburg appear at the very end of Warm Fuzzy Plains and attempt to stop Mario from getting the Comet Piece. After they come out of hiding, or if Mario approaches their hiding spot, these Goombas initiate battle, and transform into Paper-Cone Goombas. After they are defeated, the Goombas run off, allowing Mario to get the nearby Comet Piece.
Paper Mario: Sticker Star
Paper Mario: Color Splash
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