Mattermouth

Mattermouths are enemies who debuted in Super Mario Galaxy 2. They resemble a Skeleton Koopa's skull as well as that of a Bone Dragon. They earned their name from a pun on "motormouth" (which means to talk incessantly super fast), and "matter", referencing how they eat matter.

Physical Appearance
Mattermouth is about as big as Mario is. He is white like Skeleton Koopas are. His jaw contains square teeth. Inside his mouth is a purple void. He has black eyes with yellow pupils.

Super Mario Galaxy 2
Mattermouths make their debut in Super Mario Galaxy 2, where Mario can find them in places such as the Haunty Halls Galaxy and Bowser's Lava Lair. If he falls into the hole Mattermouth creates as he destroys the ground, Mario will lose a life. Mattermouth will turn around if you stomp on his head as he is travelling, though this is risk. Mario will also lose some of his health if he touches these enemies elsewhere, such as getting caught in their path.

Mario Party: Island Tour
Mattermouths make their final appearance in Mario Party: Island Tour. The mini game Mind Over Mattermouth involves these enemies tearing away at a carpet with their feasting, hence the game's name. The players have to stand on the carpet's remains to score points (1 point per second). If they fall, they stop earning points. Whoever has the most points at the end (that is, the one who survives the longest) wins. Mattermouth will also stun anyone he collides with in this game.