different from the other ones Samus finds in the game, as their structures seem to have greatly aged (and are starting to break down) with time and are more avian-looking. Unlike the other upgrades in the game, unknown items have a dull grey colour and do not glow; like the statues, they appear to be very old. Initially, they are unusable by Samus Aran as upgrades, but allow her to destroy certain blocks bearing images of the associated Unknown Item. Until the player defeats the Chozo Hieroglyphic late in the game, the Unknown Items appear as garbled, mixed up text of an unknown language on the inventory screen. After defeating the Chozo Hieroglyphic, the Unknown Items' true identities are revealed to be the Gravity Suit, Plasma Beam, and Space Jump. A Japanese interview stated that they work because the Power Suit that Samus gains here is a "legendary one"[citation needed], and therefore compatible with older technologies. This suit is known to be more resistant to damage, and to increase muscle mass by 10%.
The Unknown Items are all items not available in the original Metroid game, and coincidentally resemble the Sacred Treasures from Kid Icarus, which used the Metroid engine: the Mirror Shield (Gravity Suit), Light Arrows (Plasma Beam), and Wings of Pegasus (Space Jump). All three were required to go to the last level of the game, and were not usable before that point.