"Star Seeds" are crystals contained in all life and are the embodiment of life itself. All planets, stars, and asteroids have a star seed. A regular star seed is within regular humans and once removed the light within it fades (turning the victims into phages according to the 90's anime). It is unknown why they turn into phages since they were only made to be the Monster-of-the-day for the anime but a possible explanation is that it was caused by Galaxia's Golden Armlet which is imbued with dark energy and can turn a normal living being into an evil Sailor Guardian.
Most of the star seeds consisted of a small glittering sphere enveloped in a hexagonal dipyramidal-shaped transparent crystal. All normal Star Seeds are a light blue-gray color. In the case of True Star Seeds, the color corresponded to their planet color.
In the anime, Galaxia's Star Seed seemed to have attained a level of sentience; it took the forms of Chibi Chibi to get close to Usagi, The Sword of Sealing to fight Chaos Galaxia, and a bright pink butterfly to fly across the galaxy. In its common appearance, it was a pink Star Seed.
If the Star Seed was retrieved, its carrier could be revived in their physical form.
Types of Star Seeds
- Normal Star Seed: Common people had weak Star Seeds. When a human was hit by the golden energy blasts produced by Sailor Galaxia's bracelets, an orange-colored flower appeared above their head or in front of their chest and opened to reveal the Star Seed, which turned black right after being forcefully exposed, and a person whose Star Seed had turned black became a Phage.
- True Star Seed: Those belonging to Sailor Guardians had a permanent shine, and were called true Star Seeds, or, in the manga, Sailor Crystals. Each planetary body in the galaxy was represented by its own Star Seed, and the Sailor Guardian of that planet was its carrier. It retains their shine even with exposure to the outside and they are held within Sailor Guardians. They withhold the power of the star they protect/have the power of. If a Sailor Guardians' Star Seed was taken out of their body, the Sailor Guardian disappeared, which was equivalent to dying, as shown in episode 196.
- It should be noted that in the manga, regular humans do not turn into phages when their Star Seeds are revealed and are taken in a similar to pure hearts during the Sailor Moon S arc.
- In the manga, Mamoru's Golden Crystal was exactly the same in appearance to Usagi's Silver Crystal (Both were lotus-shaped).
- Usagi's Star Seed is revealed by Sailor Galaxia in the first anime as the most brilliant and pure Star Seed in the galaxy.