Treevil

Treevil is an odd-looking walking tree enemy found in Mario & Luigi: Bowser's Inside Story. It appears in two forms: one with sad glowing blue eyes, and one with malicious red eyes, holding a nut on their branches. Depending on who the player is playing as, the Treevil will attack in a different pattern. Treevil throws twigs at the character. While playing as Bowser, Treevil will either lob the twig or throw it straight. Bowser has to punch the twig when it's thrown straight and duck under his shell when it gets lobbed. Bowser can also inhale the nut on the red-eyed Treevil to replenish HP.

Trivia
They bear a resemblance to the eyed trees seen in Forever Forest in Paper Mario.