Bony Beetle

A Bony Beetle is an undead skeletal version of a Buzzy Beetle that has made appearances as uncommon enemies throughout the Mario franchise.

Super Mario World
They first appear in Super Mario World and its remake; they mostly appear in castles in fortresses, where they walk around, then stop and stick out spikes. Bony Beetles are first seen in the depths of Vanilla Fortress. They can be defeated with the swing of a cape, but are immune to Fireballs. If Mario stomps one, it will fall apart and reassemble seconds later, similar to a Dry Bones. Due to graphical limitations in the original version, Bony Beetles appear to turn into Dry Bones whenever they collapse.

Super Mario Advance 4: Super Mario Bros. 3
Bony Beetles also appear in the World-e level Swinging Bars of Doom from Super Mario Advance 4: Super Mario Bros. 3. They look and act the same exact way as in Super Mario World.

New Super Mario Bros. U
Bony Beetles reappear in the Wii U game, New Super Mario Bros. U, making their first HD appearance. Their behavior is exactly the same as in Super Mario World; they walk around and suddenly stop to stick out their spikes. When stomped, they fall apart and reform a few seconds later; immediately after reforming, they will always stick their spikes out before walking around again. Notably, they now resemble their Paper Mario: Sticker Star appearance, and are quadrupedal, making them closer in appearance to Buzzy Beetles.

They typically appear in later Towers and Castles, but they can also appear in volcanic and subterranean levels as well. Bony Beetles can be defeated with an Ice Flower, or by hitting elastic platforms underneath them.

Super Mario-Kun
A giant Bony Beetle has appeared in volume 4 of Super Mario-Kun, which deals with Super Mario World. Unlike in the games, it can shoot spikes to form a prison-like structure and shoot lasers from its eyes. When it rams into Mario, it sends Mario flying into a block, releasing a Dragon Coin. When Yoshi grabs the Dragon Coin, his tongue swirls out of control and defeats the Bony Beetle.

Paper Mario
They are later seen in Paper Mario in an underground section of Bowser's Castle (and several other places). If they spot Mario, they will try to land a First Strike with a Shell Toss attack. They attack in different ways depending on if their back spikes are extended: If their spikes stick out, they jump onto Mario, doing five damage, and cannot be jumped on; if their spikes are retracted, they simply use a basic Shell Toss attack like a Koopa Troopa for three damage instead. They will retract or extend their spikes after being attacked by Mario and his partners.

Paper Mario: Sticker Star
Bony Beetles appear as enemies in the Nintendo 3DS game Paper Mario: Sticker Star. Their appearance now closely resembles Buzzy Beetles more than their previous iterations. Just like in Paper Mario, Bony Beetles can protrude and retract their spikes at will, and are also immune to fire-based attacks. They cannot be jumped on unless Mario uses an Iron Jump sticker; if he uses one when the spikes are not displayed, they simply repel the attack by extending their spikes. A Bony Beetle's only attack is protruding their spikes (if they have not already) and then headbonking Mario; much like a Goomba, the Bony Beetle will roll over if the attack misses.

Their appearance in this game was later used in New Super Mario Bros. U, as stated above.

Mario Party: Island Tour
Bony Beetles appear in Mario Party: Island Tour on the Star-Crossed Skyway board. In the second and third Star Stages, a Bony Beetle gives out two Mini Ztars. When idle, it has its head out and its spines retracted, but when it first appears and when the player receives the Mini Ztars, it pulls its head into its shell and sticks out its spikes.

Trivia

 * In Super Mario World, Bony Beetles have red shoes, but the one shown in the credits cutscene for the game has blue shoes.