Bone Piranha Plant

Bone Piranha Plants are a variety of undead Piranha Plant debuting in New Super Mario Bros. 2. They are skeletal versions of normal Piranha Plants with some changes, such as a grayish cranium, holes rather than spots, light cyan lips, vertebrae instead of a plant stalk, and dark, gray leaves that appear dead.

New Super Mario Bros. 2
Besides these graphic changes, its attack patterns appear the same than those of a regular Piranha Plant. However, unlike normal Piranha Plants, and like Dry Bones, they are immune to fireballs. They can be defeated by a Super Leaf tail spin, Super Star, or a Gold Flower, however. They are only found in Towers and Castles. They are also extremely common throughout.

Mario Party: Island Tour
Bone Piranha Plants also appear in Mario Party: Island Tour on the Bowser's Peculiar Peak board. If the player lands on a space that moves them forward a number of spaces, the Bone Piranha Plant appears, chews them up, and then throws them forward.

Mario Kart 8 / Mario Kart 8 Deluxe
In Mario Kart 8 and Mario Kart 8 Deluxe, Bone Piranha Plants appear as obstacles on Bone-Dry Dunes. Here, they behave just like other Piranha Plants in the Mario Kart series, trying to bite nearby drivers.

Puzzle & Dragons: Super Mario Bros. Edition
Bone Piranha Plants are present in Puzzle & Dragons: Super Mario Bros. Edition, where they own the Wood attribute, but also the Dark attribute. As such, they appear to be very weak to the Fire attribute, yet strong to the Water one. They show a lack in HP and RCV ratings, but this is completed by their dangerous amount of attack points. Poison Mist is the name of their main skill, which switches Water and Fire orbs of enemies to their own attribute orbs - Wood and Dark, respectively.

Bone Piranha Plants are typically found at the Tower courses, along with the Big Bone Piranha Plant, but they can also appear in a few courses at World 8 and ★World 8. When fought as enemies, they attack every two turns, and can even poison the player's team.

Other appearances
In Super Smash Bros. Ultimate, Bone Piranha Plants (just called Bone Piranhas) are mentioned briefly by Viridi during Palutena's Guidance dialogue for Piranha Plant. Piranha Plant's white colors references a Bone Piranha Plant.