Piranhacus Giganticus

Piranhaci Gigantici (singular Piranhacus Giganticus) is a gigantic Piranha Plant that first appeared in the game Super Mario Bros. 3. Unlike Big Piranha Plants, they are seen in pipes.

Super Mario Bros. 3
In Super Mario Bros. 3, they only appear in Giant Land. Although they are huge, a single fireball will destroy them. Despite their size, they are essentially exactly the same as any other typical Piranha Plant, other than they present a larger target and obstacle. They also appear in larger Warp Pipes than other Piranha Plants. Most of them are red, except for the ones in World 4-6, which are green.

Super Mario Galaxy 2
Piranhacus Gigantici appear alongside Grand Goombas, Giant Land Paragoombas, and Gargantua Koopa Troopas in the Wii game, Super Mario Galaxy 2, where they appear in the Supermassive Galaxy. They are similar to how they appear in Super Mario Bros 3 only a lot bigger. However, in contrast to their original appearance in Super Mario Bros. 3, they are invincible, thus serving more as an obstacle than an enemy. They can, however, be stunned with a Spin or a Star Bit, but that just hinders the player as it stops the plant from going back in the pipe.

New Super Mario Bros. U
Piranhacus Gigantici reappear in New Super Mario Bros. U. They act the same way they did in Super Mario Bros. 3 although this time need to be hit with three Fireballs to be defeated, similar to Big Piranha Plants, yet they can also be defeated with Gargantua Koopa Troopa shells as well. They are found in Soda Jungle, more specifically in Jungle of the Giants, which is the only level they appear in.

Mario Golf: World Tour
Piranhacus Gigantici appear in Mario Golf: World Tour on Hole 6 of Wiggler Park. As a reference to Super Mario 64, they are originally found sleeping, although being hit by the ball will cause them to wake up.

Trivia

 * Piranhacus Giganticus' name is given in binomial nomenclature, a scientific way of naming species, with the words 'piranha' and 'gigantic' altered to fit the Latin grammatical form.