Naraoia was an arthropod. From what we can tell, it inherited the characteristics of an early arthropod, including jointed legs.
In fact, Naraoiaís legs tell an interesting story. Scientists first thought that Naraoia was a crustacean. But in the 1970s, scientists discovered that many Cambrian fossils were preserved in three dimensions. By cutting through the top layers of a Naraoia fossil to its underbelly, researchers were able to see exactly how its legs attached to its body, and this detail revealed that Naraoia had the legs of a trilobite an extinct group of arthropods not those of a crustacean.
Trilobites evolved during or before the Cambrian, and became marvelously diverse soon after. Five hundred million years ago, they were the rulers of the oceans. However, the entire lineage went extinct 245 million years ago. Naraoia probably branched off of the trilobite lineage early before the more typical trilobite characteristics evolved.