List of Objects

As Mario and Luigi explore the plexus, they will come across a variety of different items and objects to help them along the way.

Stars
These are your main objective and what you'll be collecting throughout most of the game.

Power Star
Scattered all throughout the castle, picking these up will (usually) add to the player's total star count. Be wary, as some may in fact be fake stars that will warp you to another location entirely.

Red Star
Red Stars are a rare variant of Power Stars that can usually be obtained from boss stages and other obscure areas. Picking these up will help the plumbers become more powerful, perhaps even powerful enough to be worthy of facing Bowser himself...

Green Star
There is currently only one Green Star in the game as of 0.9, located in the Genesis Basement. Its purpose or use is currently unknown.

Cap Switches
Pressing these will usually reward the player with access to new powerups.

Red Cap Switch
Activates all Red ? Blocks in the world, allowing use of the Wing Mario power up. Can be found in Wing Cap by the Rainbow Highway and Tower of the Wing Cap (beta).

Blue Cap Switch
Activates all Blue ? Blocks in the world, allowing use of the Vanish Mario power up. Can be found in Vanish Cap within the Plexus and Uncanny Moat.

Green Cap Switch
Activates all Green ? Blocks in the world, allowing use of the Metal Mario power up. Can be found in Lethal Cavern and Jolly Roger Lagoon.

Yellow Switch
Pressing this probably isn't a good idea. Can be found in Bob-omb Cavern and the Holy Yellow Switch Palace.

Yellow ? Block
A regular item box. Usually contains an assortment of coins, but may also rarely contain Stars or, on a few occasions, nothing at all.

Red ? Block
Breaking this block releases a Wing Cap, which turns Mario into Wing Mario, allowing you to fly anywhere, in any direction, without the need for momentum.

Blue ? Block
Breaking this block releases a Vanish Cap, which turns Mario into Vanish Mario. Vanish Mario can run through certain mirrors and walls with ease.

Green ? Block
Breaking this block releases a Metal Cap, which turns Mario into Metal Mario. Metal Mario is very heavy, sinking to the bottom of any liquids, and is also completely immune to all forms of damage.

Ultimate ? Block
A unique ? Block found only in Goomboss Battle, this block releases all 3 caps at once, turning Mario into Ultimate Mario. This block can only be broken once per visit, and does not respawn after the caps wear off.

If not all of the cap switches have been pressed in a given save file, then the Ultimate ? Block will have a slightly altered appearance and only drop the caps the player currently has unlocked.

Collectables
These are objects usually found in levels and are required either to obtain Power Stars or progress more through the level.

Red Coins
Like in vanilla Mario 64, Red Coins can be found in most regular courses in the game. Picking one up refills 2 slices of health, and also

Silver Stars (Bouncing)
These stars are only pieces of a Power Star, and all 5 must be brought together to make it whole again! They will bounce around the level aimlessly until collected.

Silver Stars (Static)
These are visually identical to the bouncing Silver Stars, except they float statically in set locations until picked up. Functionally, they are identical to Red Coins and appear as such in the pause menu, but only 5 are usually needed to assemble the Power Star.

Mini Stars
Mini Stars are a rarer type of collectable that are functionally identical to Red Coins, outside of providing a different aesthetic.

Keys
Keys are collectables usually found in Ghost-themed levels. There are two different types of keys; the first type are static objects that must be picked up, like Red Coins, rewarding a Power Star when all 5 are found. The second type is more common, and actually act as keys which are used to open otherwise locked doors in a given level. These variants are typically found inside Boo enemies who must be defeated first to collect the key inside.

Trivia

 * The Ultimate ? Block's appearance is visually distinct from all the other functional cap blocks in the game, more closely resembling their Super Mario Bros. appearance.
 * The Metal Cap that emerges from the Ultimate ? Block appears as a smaller version of the block itself. It otherwise functions exactly as intended, granting the player its usual abilities.
 * The graphics for Red and Silver Stars are actually present in the official Super Mario 64, visible on the title screen spinning around Mario's head.
 * The Bouncing Silver Stars are a direct reference to the ones in Super Mario 64 DS, even playing the exact same jingle when picking one of them up.