Dry Bones

Dry Bones are skeletal variants of the Koopa found in certain personalized copies. They usually either function as a reskin of the Koopa similarly to Enemy Discoloring, or will function the same as Dry Bones in other Super Mario Bros. games, falling apart upon being jumped on and later putting itself back together.

Dry Bones have been reported to be invincible due to their behavior, though can sometimes be defeated using the Metal Cap. Dry Bones have mainly been reported in Big Boo's Forest and Dry Bones Desert, though have also occasionally be reported in the outside of Big Boo's Haunt and Hazy Maze Cave.

Pyramid Variant
A variant of Dry Bones, commonly known by players as Mummy Koopas, appear within Shifting Sand Land's pyramid in some copies. Their behavior matches their normal variant, but their textures include bandages that give them the appearance of a mummified zombie. Supposedly, their rattling noises include the sounds of shifting and falling sand being thrown about inside their bodies.