Panser

Pansers are enemies commonly found in Super Mario Bros. 2. Along with Pokeys, they are the only known hostile plant species in Subcon, although Pansers were created by Wart. There are four types of Pansers: red, green, gray and pink. The red version will stay in one place and shoot three fireballs in Mario's, Luigi's, Toad's, or Princess Peach's direction, green and gray (just green in the remake) will patrol an area and shoot fireballs straight up, and the most powerful, the pink (blue in the remake), will chase Mario or his friends and shoot three fireballs. These enemies can only be defeated by throwing another enemy or a Mushroom Block at them, and are sometimes an excessively annoying enemy. They somewhat resemble Fire Flowers.

They are much like the Volcano Lotus and the Lava Lotus (as well as Pompon Flowers) of later games. A key difference between Panser and the Lotus enemies is that the former walks and is more aggressive, whereas the latter are immobile and seem to be defending themselves.

No actual Panser is found outside of Super Mario Bros. 2, its remakes, and other related media. Nonetheless, in the racetrack titled Shy Guy Bazaar from Mario Kart 7, many stalls (and even part of the track itself) are decorated with red carpets, all of which feature Panser sprites as motifs, along with Phantos and Cobrats.

Trivia

 * Excluding Wart, Pansers were the only enemy from Super Mario Bros. 2 to not appear in The Super Mario Bros. Super Show!; though they were possibly amalgamated with the Piranha Plant as Magic Piranha Plant, which could also exhale fireballs.
 * Pansers likely got their name a combination of the word pansy, a type of flower, and Panzer, a German tank, perhaps in reference to the plant's ability to throw fireballs.
 * In Super Mario Bros. 3, the game's sole Fiery Walking Piranha at the end of World 7-8 acts similar to a red Panser but shoots four fireballs instead of just three.