Trampoline

The Trampoline is an unfinished and unused object in Super Mario 64. Its model and collision are nearly fully finished, but its code was apparently abandoned early on.

Trampoline
Hitbox Info
Hitbox	Collision involves triangles instead of a cylindrical hitbox
Tangibility radius	1000
Interaction type	None
Surfaces	0x00 (default)

The game contains infrastructure for the trampoline to affect Mario's jumps, and the trampoline has code for visually stretching and compressing. However, if you manage to load the trampoline into the game, it doesn't do anything other than act as a platform since there is no code to move it nor code to interface it with the existing trampoline infrastructure.