Sockop

Sockops are sock-like pitcher plant enemies encountered in Dimble Wood in Mario & Luigi: Bowser's Inside Story. If Mario or Luigi try to jump on them, they will be sucked into the hole on the top of the Sockop's head. They will then have to mash A or B repeatedly in order to escape, otherwise they may be damaged or poisoned. They attack by tackling the brothers. Normally, they run at one brother, then turn around and run at them again. However, if some honey comes out of the top, they will charge at the first brother and go offscreen, coming back to hit the other brother from behind. Later in the game, Mario is captured by the Sockops and Luigi has to rescue him, getting stuck inside a Sockop in the process. While he is stuck inside the Sockop, Luigi can communicate with them, and doesn't have to fight them. He can also traverse the bramble patches spread throughout the wood. They have a boss - one giant Sockop, that is shrunk down to normal size during the events in the game, and they enjoy eating Attack Piece Blocks. This aformentioned boss is the sockop that Luigi ends up using as a "puppet".

Trivia

 * Sockops are similar to the Kuribo's Shoe, a power-up found in Super Mario Bros. 3. At a certain point, it's even used to ride and hop on thorns. In addition, one Sockop's name is revealed to be Kuribo.
 * Sockops are based on a pitcher plant, a type of carnivorous flower.