Porunga is the eternal dragon
of the Namek dragonballs.
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Dragonballs are very important in Dragonball, Z, and GT, aside from being part of the title. These 7 balls are usually created by some kind of supreme being on a planet. On Earth Kami created the dragonballs and on Namek the Senior Elder created the dragonballs. On Earth the dragonballs are about the size the size of Florida oranges; on Namek the dragonballs are about the size of your average beachball. The dragonballs need to be collect (all 7) in one place and then one must summond the eternal dragon. The Earth dragon is named Shenlon(above), you might see it spelled Shenron else where but "L" and "R" are interchangable in Japanese. And the Namek dragon is named Porunga(below). This is important: The dragons cannot grant a wish that is beyond the power of their creator. But after a wish has been granted the dragonballs turn to stone for a year and scatter all over the globe, thus needing to be gathered again if a wish needs to be granted. The Namek dragonballs also turn to stone after their use but refresh in 130 days. Bulma is the inventor of a device that will locate dragonballs so the Z crew can find them fairly easily. Shenlon can grant one wish only, while Porunga can grant three, however Porunga is slightly weaker (i.e. he can only bring back one person at a time). Sidenote: one can only be brought back to life by the dragonballs once. But near the end of the Buu saga we learn the Namek Elder has given Porunga a power up so he can bring multiple people back.